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 (36895)
An issue was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) A use-after-free vulnerability in the write_interleaved method allows an attacker to cause a denial of service or memory corruption. 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 was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) An integer overflow vulnerability in the Vector::new constructor function allows an attacker to cause a denial of service via a null. 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 was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) Integer overflow and invalid input vulnerability in the cached method allows an attacker to cause a denial of service or potentially. 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 was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) A null pointer dereference vulnerability in the input() constructor function allows an attacker to cause a denial of service. 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 was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) Null pointer dereference vulnerability in the name() method allows an attacker to cause a denial of service. 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 was discovered in rust-ffmpeg 0.3.0 (after comit 5ac0527) Null pointer dereference vulnerability in the dump() method allows an attacker to cause a denial of service. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Undertow, a Java web server used across Red Hat's JBoss Enterprise Application Platform, Fuse, and other middleware products, contains a vulnerability that allows attackers to trigger server-side HTTP/2 stream resets without incrementing abuse counters. This 'MadeYouReset' attack enables remote unauthenticated attackers to cause denial of service by repeatedly forcing the server to abort streams and perform unnecessary cleanup work. With an EPSS score of 1.17% (78th percentile), exploitation probability is moderate but rising, and patches have been released across multiple Red Hat product lines as of early 2025.
E3 Site Supervisor Control (firmware version < 2.31F01) MGW contains an API call that lacks input validation. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A vulnerability has been identified within Rancher Manager in which it did not enforce request body size limits on certain public (unauthenticated) and authenticated API endpoints. Rated high severity (CVSS 8.2), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In geniezone, there is a possible memory corruption due to use after free. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In mbrain, there is a possible memory corruption due to use after free. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. No vendor patch available.
In monitor_hang, there is a possible memory corruption due to use after free. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. No vendor patch available.
In Modem, there is a possible out of bounds read due to an incorrect bounds check. Rated medium severity (CVSS 6.5), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A stack-based buffer overflow vulnerability in NetSupport Manager 14.x versions prior to 14.12.0000 allows a remote, unauthenticated attacker to cause a denial of service (DoS) or potentially leak a. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A heap-based buffer overflow vulnerability in NetSupport Manager 14.x versions prior to 14.12.0000 allows a remote, unauthenticated attacker to cause a denial of service (DoS) or execute arbitrary. Rated critical severity (CVSS 9.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
gnark is a zero-knowledge proof system framework. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
nptd-rs is a tool for synchronizing your computer's clock, implementing the NTP and NTS protocols. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A security flaw has been discovered in mixmark-io turndown up to 7.2.1. Rated medium severity (CVSS 5.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect Qsync Central. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. Rated medium severity (CVSS 5.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect Qsync Central. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect Qsync Central. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An allocation of resources without limits or throttling vulnerability has been reported to affect Qsync Central. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An allocation of resources without limits or throttling vulnerability has been reported to affect Qsync Central. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An allocation of resources without limits or throttling vulnerability has been reported to affect File Station 5. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An allocation of resources without limits or throttling vulnerability has been reported to affect File Station 5. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An uncontrolled resource consumption vulnerability has been reported to affect Qsync Central. Rated medium severity (CVSS 6.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An allocation of resources without limits or throttling vulnerability has been reported to affect File Station 5. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Buffer Overflow in the URI parser of CivetWeb 1.14 through 1.16 (latest) allows a remote attacker to achieve remote code execution 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.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Exiv2 is a C++ library and a command-line utility to read, write, delete and modify Exif, IPTC, XMP and ICC image metadata. Rated low severity (CVSS 1.8), this vulnerability is no authentication required, low attack complexity. This Out-of-bounds Read vulnerability could allow attackers to read data from memory outside the intended buffer boundaries.
xz is a pure golang package for reading and writing xz-compressed files. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A malicious user may submit a specially-crafted complex payload that otherwise meets the default request size limit which results in excessive memory and CPU consumption of Vault. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Improper input validation in firmware of some Solidigm DC Products may allow an attacker with local access to cause a Denial of Service. Rated medium severity (CVSS 4.4), this vulnerability is low attack complexity. No vendor patch available.
Asterisk is an open source private branch exchange and telephony toolkit. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
A heap-based buffer overflow vulnerability exists in the exists in the network-facing input handling routines of Arcserve Unified Data Protection (UDP). Rated critical severity (CVSS 9.2), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
If a DHCPv4 client sends a request with some specific options, and Kea fails to find an appropriate subnet for the client, the `kea-dhcp4` process will abort with an assertion failure. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
D-Link DCS-825L firmware v1.08.01 contains a vulnerability in the watchdog script `mydlink-watch-dog.sh`, which blindly respawns binaries such as `dcp` and `signalc` without verifying integrity,. Rated medium severity (CVSS 6.6), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
An issue has been discovered in GitLab CE/EE affecting all versions from 14.1 before 18.1.5, 18.2 before 18.2.5, and 18.3 before 18.3.1 that that under certain conditions could have allowed an. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue has been discovered in GitLab CE/EE affecting all versions from 8.15 before 18.1.5, 18.2 before 18.2.5, and 18.3 before 18.3.1 that could have could have allowed an authenticated user to. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability in the Protocol Independent Multicast Version 6 (PIM6) feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software for Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS. Rated high severity (CVSS 7.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In multiple functions of sdp_server.cc, there is a possible use after free due to a logic error in the code. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In process_service_attr_rsp of sdp_discovery.cc, there is a possible use after free due to a logic error in the code. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In multiple locations, there is a possible way to execute arbitrary code due to a use after free. Rated high severity (CVSS 8.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In rfc_send_buf_uih of rfc_ts_frames.cc, there is a possible way to execute arbitrary code due to a use after free. Rated high severity (CVSS 8.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In rfc_check_send_cmd of rfc_utils.cc, there is a possible way to execute arbitrary code due to a use after free. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In hidd_check_config_done of hidd_conn.cc, there is a possible way to execute arbitrary code due to a use after free. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In bnepu_check_send_packet of bnep_utils.cc, there is a possible way to achieve code execution due to a use after free. Rated high severity (CVSS 8.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In multiple locations, there is a possible way to execute arbitrary code due to a use after free. Rated high severity (CVSS 8.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In avct_lcb_msg_ind of avct_lcb_act.cc, there is a possible way to execute arbitrary code due to a use after free. Rated high severity (CVSS 8.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In sdp_snd_service_search_req of sdp_discovery.cc, there is a possible way to execute arbitrary code due to a use after free. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In multiple locations, there is a possible out of bounds write due to a use after free. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In dng_lossless_decoder::HuffDecode of dng_lossless_jpeg.cpp, there is a possible way to cause a crash due to uninitialized data. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In process_service_search_attr_req of sdp_server.cc, there is a possible way to execute arbitrary code due to a use after free. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In process_service_attr_rsp of sdp_discovery.cc, there is a possible way to execute arbitrary code due to a use after free. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In multiple locations, there is a possible crash loop due to resource exhaustion. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In btif_hh_hsdata_rpt_copy_cb of bta_hh.cc, there is a possible way to corrupt memory due to a use after free. Rated high severity (CVSS 8.0), this vulnerability is low attack complexity. No vendor patch available.
Use after free in ANGLE in Google Chrome prior to 139.0.7258.154 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
ImageMagick is free and open-source software used for editing and manipulating digital images. Rated low severity (CVSS 3.7), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.
jsPDF is a library to generate PDFs in JavaScript. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Memory overflow vulnerability leading to unpredictable or erroneous behavior and Denial of Service in NetScaler ADC and NetScaler Gateway when NetScaler is configured as a Gateway (VPN virtual. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Citrix NetScaler ADC and Gateway contain a memory overflow vulnerability enabling remote code execution and denial of service when configured as VPN, AAA, or load balancing virtual servers.
A NULL pointer dereference vulnerability has been reported to affect File Station 5. Rated high severity (CVSS 7.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A denial of service vulnerability exists in the JSONReader component of the run-llama/llama_index repository, specifically in version v0.12.37. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
D-Link DI-8100 16.07.26A1 is vulnerable to Buffer Overflow via the en`, `val and id parameters in the qj_asp function. Rated high severity (CVSS 7.0), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.
Adminer 4.8.1, when using Monolog for logging, allows a Denial of Service (memory consumption) via a crafted serialized payload (e.g., using s:1000000000), leading to a PHP Object Injection issue. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A security flaw has been discovered in Open5GS up to 2.7.5. Rated medium severity (CVSS 5.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
A vulnerability was determined in jqlang jq up to 1.6. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A security flaw has been discovered in ckolivas lrzip up to 0.651. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A flaw has been found in PoDoFo 1.1.0-dev.cpp of the component PDF Dictionary Parser. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available.
A vulnerability has been found in appneta tcpreplay up to 4.5.1. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A flaw has been found in appneta tcpreplay up to 4.5.1. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability was detected in appneta tcpreplay up to 4.5.1. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. Public exploit code available and no vendor patch available.
Self-ReDoS (Regular expression Denial of Service) exists with Role Name search field of Kaleo Designer portlet JavaScript in Liferay Portal 7.4.0 through 7.4.3.131, and Liferay DXP 2024.Q4.0 through. Rated medium severity (CVSS 6.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Liferay Portal 7.4.0 through 7.4.3.132, and Liferay DXP 2025.Q1.0 through 2025.Q1.1, 2024.Q4.0 through 2024.Q4.7, 2024.Q3.1 through 2024.Q3.13, 2024.Q2.0 through 2024.Q2.13, 2024.Q1.1 through. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Incorrect access control in the RTMP server settings of Reolink Smart 2K+ Plug-in Wi-Fi Video Doorbell with Chime - firmware v3.0.0.4662_2503122283 allows unauthorized attackers to cause a Denial of. 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.
Reolink Smart 2K+ Plug-in Wi-Fi Video Doorbell with Chime - firmware v3.0.0.4662_2503122283 was discovered to manage users' sessions system wide instead of an account-by-account basis, potentially. Rated medium severity (CVSS 4.0), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
In the Linux kernel, the following vulnerability has been resolved: Revert "drm/prime: Use dma_buf from GEM object instance" This reverts commit f83a9b8c7fd0557b0c50784bfdc1bbe9140c9bf8. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
In the Linux kernel, the following vulnerability has been resolved: Revert "drm/gem-framebuffer: Use dma_buf from GEM object instance" This reverts commit cce16fcd7446dcff7480cd9d2b6417075ed81065. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.