Denial of Service
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
How It Works
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions. Attackers exploit asymmetry: minimal attacker effort produces disproportionate resource consumption on the target. Application-level attacks use specially crafted inputs that trigger expensive operations—a regex engine processing malicious patterns can backtrack exponentially, or XML parsers recursively expand entities until memory exhausts. Network-level attacks flood targets with connection requests or amplify traffic through reflection, but application vulnerabilities often provide the most efficient attack surface.
The attack typically begins with reconnaissance to identify resource-intensive operations or unprotected endpoints. For algorithmic complexity attacks, adversaries craft inputs hitting worst-case performance—hash collision inputs filling hash tables with collisions, deeply nested JSON triggering recursive parsing, or pathological regex patterns like (a+)+b against strings of repeated 'a' characters. Resource exhaustion attacks open thousands of connections, upload massive files to unbounded storage, or trigger memory leaks through repeated operations. Crash-based attacks target error handling gaps: null pointer dereferences, unhandled exceptions in parsers, or assertion failures that terminate processes.
Impact
- Service unavailability preventing legitimate users from accessing applications during attack duration
- Revenue loss from downtime in e-commerce, SaaS platforms, or transaction processing systems
- Cascading failures as resource exhaustion spreads to dependent services or database connections pool out
- SLA violations triggering financial penalties and damaging customer trust
- Security team distraction providing cover for data exfiltration or intrusion attempts running concurrently
Real-World Examples
CVE-2018-1000544 in Ruby's WEBrick server allowed ReDoS through malicious HTTP headers containing specially crafted patterns that caused the regex engine to backtrack exponentially, freezing request processing threads. A single attacker could saturate all available workers.
Cloudflare experienced a global outage in 2019 when a single WAF rule containing an unoptimized regex hit pathological cases on legitimate traffic spikes. The .*(?:.*=.*)* pattern exhibited catastrophic backtracking, consuming CPU cycles across their edge network until the rule was disabled.
CVE-2013-1664 demonstrated XML bomb vulnerabilities in Python's XML libraries. Attackers uploaded XML documents with nested entity definitions-each entity expanding to ten copies of the previous level. A 1KB upload could expand to gigabytes in memory during parsing, crashing applications instantly.
Mitigation
- Strict input validation enforcing size limits, complexity bounds, and nesting depth restrictions before processing
- Request rate limiting per IP address, API key, or user session with exponential backoff
- Timeout enforcement terminating operations exceeding reasonable execution windows (typically 1-5 seconds)
- Resource quotas limiting memory allocation, CPU time, and connection counts per request or tenant
- Regex complexity analysis using linear-time algorithms or sanitizing patterns to eliminate backtracking
- Circuit breakers automatically rejecting requests when error rates or latency thresholds indicate degradation
- Load balancing and autoscaling distributing traffic across instances with automatic capacity expansion
Recent CVEs (40209)
Valinor is a PHP library that helps to map any input into a strongly-typed value object structure. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
KubeEdge is an open source system for extending native containerized application orchestration capabilities to hosts at Edge. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
KubeEdge is an open source system for extending native containerized application orchestration capabilities to hosts at Edge. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
In CmpChannelServer of CODESYS V3 in multiple versions an uncontrolled ressource consumption allows an unauthorized attacker to block new communication channel connections. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In CmpBlkDrvTcp of CODESYS V3 in multiple versions an uncontrolled ressource consumption allows an unauthorized attacker to block new TCP connections. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
softmmu/physmem.c in QEMU through 7.0.0 can perform an uninitialized read on the translate_fail path, leading to an io_readx or io_writex crash. Rated high severity (CVSS 8.8), this vulnerability is low attack complexity. Public exploit code available.
Use After Free in GitHub repository vim/vim prior to 9.0.0046. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
In Eclipse Jetty HTTP/2 server implementation, when encountering an invalid HTTP/2 request, the error handling has a bug that can wind up not properly cleaning up the active connections and. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An infinite loop in the function httpRpmPass of TP-Link TL-WR741N/TL-WR742N V1/V2/V3_130415 allows attackers to cause a Denial of Service (DoS) via a crafted packet. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Akashi is an open source server implementation of the Attorney Online video game based on the Ace Attorney universe. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Hyperledger Fabric is a permissioned distributed ledger framework. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A memory corruption in Hex Rays Ida Pro v6.6 allows attackers to cause a Denial of Service (DoS) via a crafted file. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
curl < 7.84.0 supports "chained" HTTP compression algorithms, meaning that a serverresponse can be compressed multiple times and potentially with different algorithms. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
A malicious server can serve excessive amounts of `Set-Cookie:` headers in a HTTP response to curl and curl < 7.84.0 stores all of them. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
A vulnerability in Cisco Smart Software Manager On-Prem (SSM On-Prem) could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
There are use-after-free vulnerabilities caused by timer handler in net/rose/rose_timer.c of linux that allow attackers to crash linux kernel without any privileges. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This Use After Free vulnerability could allow attackers to access freed memory to execute arbitrary code or crash the application.
moment is a JavaScript date library for parsing, validating, manipulating, and formatting dates. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Gallagher Controller 6000 is vulnerable to a Denial of Service attack via conflicting ARP packets with a duplicate IP address. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In MDP, there is a possible use after free due to a race condition. Rated medium severity (CVSS 6.4). No vendor patch available.
In sched driver, there is a possible use after free due to improper locking. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In TEEI driver, there is a possible use after free due to a race condition. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In TEEI driver, there is a possible use after free due to a race condition. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In GED driver, there is a possible use after free due to a race condition. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In GPU, there is a possible use after free due to a race condition. Rated high severity (CVSS 7.0). No vendor patch available.
quic-go through 0.27.0 allows remote attackers to cause a denial of service (CPU consumption) via a Slowloris variant in which incomplete QUIC or HTTP/3 requests are sent. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
IBM App Connect Enterprise Certified Container 4.2 could allow a user from the administration console to cause a denial of service by creating a specially crafted request. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Arm guests can cause Dom0 DoS via PV devices When mapping pages of guests on Arm, dom0 is using an rbtree to keep track of the foreign mappings. Rated medium severity (CVSS 4.7).
NULL Pointer Dereference allows attackers to cause a denial of service (or application crash). Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Zoho ManageEngine ADSelfService Plus before 6203 allows a denial of service (application restart) via a crafted payload to the Mobile App Deployment API. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the IpSecDxe, where a user with high privileges and preconditioned IpSecDxe global data can exploit improper validation of an array index to cause. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the IpSecDxe, where a user with elevated privileges and a preconditioned heap can exploit an out-of-bounds write vulnerability, which may lead to. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the SmbiosPei, which may allow a highly privileged local attacker to cause an out-of-bounds write, which may lead to code execution, denial of. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the SmmCore, where a user with high privileges can chain another vulnerability to this vulnerability, causing an integer overflow, possibly. Rated high severity (CVSS 8.2), this vulnerability is low attack complexity. No vendor patch available.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the Ofbd, where a local user with elevated privileges can cause access to an uninitialized pointer, which may lead to code execution, escalation. Rated high severity (CVSS 8.2), this vulnerability is low attack complexity. No vendor patch available.
Use After Free in GitHub repository vim/vim prior to 9.0. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
NVIDIA DGX A100 contains a vulnerability in SBIOS in the BiosCfgTool, where a local user with elevated privileges can read and write beyond intended bounds in SMRAM, which may lead to code execution,. Rated high severity (CVSS 8.2), this vulnerability is low attack complexity. No vendor patch available.
MariaDB v10.5 to v10.7 was discovered to contain an assertion failure at table->get_ref_count() == 0 in dict0dict.cc. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
All versions of package scss-tokenizer are vulnerable to Regular Expression Denial of Service (ReDoS) via the loadAnnotation() function, due to the usage of insecure regex. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
NVFLARE, versions prior to 2.1.2, contains a vulnerability in its utils module, where YAML files are loaded via yaml.load() instead of yaml.safe_load(). Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
NVFLARE, versions prior to 2.1.2, contains a vulnerability in its PKI implementation module, where The CA credentials are transported via pickle and no safe deserialization. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A Regular Expression Denial of Service vulnerability in GitLab CE/EE affecting all versions from 1.0.2 prior to 14.10.5, 15.0 prior to 15.0.4, and 15.1 prior to 15.1.1 allows an attacker to make a. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
NULL Pointer Dereference in GitHub repository bfabiszewski/libmobi prior to 0.11. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
A stack overflow in the function DM_ In fillobjbystr() of TP-Link Archer C50&A5(US)_V5_200407 allows attackers to cause a Denial of Service (DoS) via a crafted HTTP request. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
An issue in the AST parser (ast/compile.go) of Open Policy Agent v0.10.2 allows attackers to cause a Denial of Service (DoS) via a crafted input. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
PingID Windows Login prior to 2.8 does not authenticate communication with a local Java service used to capture security key requests. Rated medium severity (CVSS 6.4). No vendor patch available.
PingID Windows Login prior to 2.8 is vulnerable to a denial of service condition on local machines when combined with using offline security keys as part of authentication. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
IBM Spectrum Protect 8.1.0.0 through 8.1.14.0 dsmcad, dsmc, and dsmcsvc processes incorrectly handle certain read operations on TCP/IP sockets. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A vulnerability was found in the Linux kernel's nft_set_desc_concat_parse() function .This flaw allows an attacker to trigger a buffer overflow via nft_set_desc_concat_parse() , causing a denial of. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity.
A NULL pointer dereference flaw was found in the Linux kernel’s KVM module, which can lead to a denial of service in the x86_emulate_insn in arch/x86/kvm/emulate.c. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity.
Joy ebike Wolf Manufacturing year 2022 is vulnerable to Denial of service, which allows remote attackers to jam the key fob request via RF. Rated medium severity (CVSS 6.8), this vulnerability is no authentication required. Public exploit code available and no vendor patch available.
RSSHub is an open source, extensible RSS feed generator. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
NULL Pointer Dereference in GitHub repository vim/vim prior to 8.2. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
Synapse is an open source home server implementation for the Matrix chat network. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
When an attacker obtaining the administrative account and password, or through a man-in-the-middle attack, the attacker could send a specified crafted packet to the vulnerable interface then lead the. Rated high severity (CVSS 7.4), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
An issue was discovered in MediaWiki through 1.38.1. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
lettersanitizer is a DOM-based HTML email sanitizer for in-browser email rendering. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
rulex is a new, portable, regular expression language. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
rulex is a new, portable, regular expression language. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
KubeEdge is built upon Kubernetes and extends native containerized application orchestration and device management to hosts at the Edge. Rated medium severity (CVSS 5.7), this vulnerability is remotely exploitable, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
KubeEdge is built upon Kubernetes and extends native containerized application orchestration and device management to hosts at the Edge. Rated medium severity (CVSS 5.7), this vulnerability is low attack complexity. Public exploit code available.
The Security Team noticed that the termination condition of the for loop in the readExternal method is a controllable variable, which, if tampered with, may lead to CPU exhaustion. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
NULL Pointer Dereference in GitHub repository vim/vim prior to 8.2.5163. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
Argo CD is a declarative continuous deployment for Kubernetes. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
IBM Db2 for Linux, UNIX and Windows 9.7, 10.1, 10.5, 11.1, and 11.5 is vulnerable to a denial of service as the server may terminate abnormally when executing specially crafted SQL statements by an. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
OFFIS DCMTK's (All versions prior to 3.6.7) has a NULL pointer dereference vulnerability while processing DICOM files, which may result in a denial-of-service condition. Rated medium severity (CVSS 6.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
An issue in gimp_layer_invalidate_boundary of GNOME GIMP 2.10.30 allows attackers to trigger an unhandled exception via a crafted XCF file, causing a Denial of Service (DoS). Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
In multiple CODESYS products, file download and upload function allows access to internal files in the working directory e.g. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
The CODESYS Gateway Server V2 does not verifiy that the size of a request is within expected limits. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In CODESYS Gateway Server V2 an insufficient check for the activity of TCP client connections allows an unauthenticated attacker to consume all available TCP connections and prevent legitimate users. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
AIOHTTP 3.8.1 can report a "ValueError: Invalid IPv6 URL" outcome, which can lead to a Denial of Service (DoS). Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Protobuf-c v1.4.0 was discovered to contain an invalid arithmetic shift via the function parse_tag_and_wiretype in protobuf-c/protobuf-c.c. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Ethereum Solidity v0.8.14 contains an assertion failure via SMTEncoder::indexOrMemberAssignment() at SMTEncoder.cpp. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
An integer overflow in the component hb-ot-shape-fallback.cc of Harfbuzz v4.3.0 allows attackers to cause a Denial of Service (DoS) via unspecified vectors. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
Lrzip v0.651 was discovered to contain multiple invalid arithmetic shifts via the functions get_magic in lrzip.c and Predictor::init in libzpaq/libzpaq.cpp. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
There is an Assertion `int decode_preR13_entities(BITCODE_RL, BITCODE_RL, unsigned int, BITCODE_RL, BITCODE_RL, Bit_Chain *, Dwg_Data *' failed at dwg2dxf: decode.c:5801 in libredwg v0.12.4.4608. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
wire-ios is an iOS client for the Wire secure messaging application. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Autodesk AutoCAD product suite, Revit, Design Review and Navisworks releases using PDFTron prior to 9.1.17 version may be used to write beyond the allocated buffer while parsing PDF files. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In Spring Cloud Function versions prior to 3.2.6, it is possible for a user who directly interacts with framework provided lookup functionality to cause a denial-of-service condition due to the. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Allocation of Resources Without Limits or Throttling in GitHub repository inventree/inventree prior to 0.8.0. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
libjxl 0.6.1 has an assertion failure in LowMemoryRenderPipeline::Init() in render_pipeline/low_memory_render_pipeline.cc. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
drivers/block/floppy.c in the Linux kernel before 5.17.6 is vulnerable to a denial of service, because of a concurrency use-after-free flaw after deallocating raw_cmd in the raw_cmd_ioctl function. Rated low severity (CVSS 3.3), this vulnerability is low attack complexity. Public exploit code available.
All versions of package pg-native; all versions of package libpq are vulnerable to Denial of Service (DoS) when the addons attempt to cast the second argument to an array and fail. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
All versions of package @discordjs/opus are vulnerable to Denial of Service (DoS) when trying to encode using an encoder with zero channels, or a non-initialized buffer. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
All versions of package fast-string-search are vulnerable to Denial of Service (DoS) when computations are incorrect for non-string inputs. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
paymentrequest.py in Electrum before 4.2.2 allows a file:// URL in the r parameter of a payment request (e.g., within QR code data). Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability was found in Ghostscript, which occurs when it tries to render a large number of bits in memory. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
OPC UA .NET Standard Stack 1.04.368 allows a remote attacker to exhaust the memory resources of a server via a crafted request that triggers Uncontrolled Resource Consumption. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
OPC UA .NET Standard Stack 1.04.368 allows a remote attacker to cause a server to crash via a large number of messages that trigger Uncontrolled Resource Consumption. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
OPC UA .NET Standard Stack 1.04.368 allows remote attacker to cause a crash via a crafted message that triggers excessive memory allocation. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Allocation of Resources Without Limits vulnerability could allow attackers to exhaust system resources through uncontrolled allocation.