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 (40207)
MZ Automation's libIEC61850 (versions 1.4 and prior; version 1.5 prior to commit a3b04b7bc4872a5a39e5de3fdc5fbde52c09e10e) uses a NULL pointer in certain situations. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
MZ Automation's libIEC61850 (versions 1.4 and prior; version 1.5 prior to commit a3b04b7bc4872a5a39e5de3fdc5fbde52c09e10e) accesses a resource using an incompatible type, which could allow an. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda W20E router V15.11.0.6 contains a stack overflow in the function formSetPortMapping with post request 'goform/setPortMapping/'. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
Mattermost version 7.1.x and earlier fails to sufficiently process a specifically crafted GIF file when it is uploaded while drafting a post, which allows authenticated users to cause resource. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A parsing vulnerability for the MessageSet type in the ProtocolBuffers versions prior to and including 3.16.1, 3.17.3, 3.18.2, 3.19.4, 3.20.1 and 3.21.5 for protobuf-cpp, and versions prior to and. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Use After Free in GitHub repository vim/vim prior to 9.0.0530. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
Improper detection of complete HTTP body decompression SwiftNIO Extras provides a pair of helpers for transparently decompressing received HTTP request or response bodies. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In Keylime before 6.3.0, quote responses from the agent can contain possibly untrusted ZIP data which can lead to zip bombs. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
XPDF 4.04 is vulnerable to Null Pointer Dereference in FoFiType1C.cc:2393. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
By sending specific queries to the resolver, an attacker can cause named to crash. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
By spoofing the target resolver with responses that have a malformed EdDSA signature, an attacker can trigger a small memory leak. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
By spoofing the target resolver with responses that have a malformed ECDSA signature, an attacker can trigger a small memory leak. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
An attacker can leverage this flaw to gradually erode available memory to the point where named crashes for lack of resources. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Memory Leak vulnerability could allow attackers to exhaust available memory leading to denial of service.
SWFTools commit 772e55a2 was discovered to contain a heap-buffer-overflow via getTransparentColor at /home/bupt/Desktop/swftools/src/gif2swf. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
A remote potential adjacent denial of service (DoS) and potential adjacent arbitrary code execution vulnerability that could potentially lead to a loss of confidentiality, integrity, and availability. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A local Denial of Service (DoS) and local arbitrary code execution vulnerability that could potentially lead to a loss of confidentiality, integrity, and availability were discovered in HPE. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. No vendor patch available.
A vulnerability exists in the ClearPass Policy Manager Guest User Interface that can allow an unauthenticated attacker to send specific operations which result in a Denial-of-Service condition. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A Regular Expression Denial of Service (ReDoS) flaw was found in stealjs steal 2.2.4 via the string variable in babel.js. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Festo control block CPX-CEC-C1 and CPX-CMXX in multiple versions allow unauthenticated, remote access to critical webpage functions which may cause a denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A security vulnerability has been identified in Apache Kafka. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An out-of-bounds read in the BGP daemon of FRRouting FRR before 8.4 may lead to a segmentation fault and denial of service. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
A denial-of-service issue was discovered in MediaWiki 1.37.x before 1.37.2. 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 flaw use after free in the Linux kernel video4linux driver was found in the way user triggers em28xx_usb_probe() for the Empia 28xx based TV cards. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity.
A heap buffer overflow issue was found in ImageMagick. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity.
Adobe Bridge version 12.0.2 (and earlier) and 11.1.3 (and earlier) are affected by a Use After Free vulnerability that could lead to disclosure of sensitive memory. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity.
Adobe Bridge version 12.0.2 (and earlier) and 11.1.3 (and earlier) are affected by a Use After Free vulnerability that could lead to disclosure of sensitive memory. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity.
Adobe Bridge version 12.0.2 (and earlier) and 11.1.3 (and earlier) are affected by a Use After Free vulnerability that could result in arbitrary code execution in the context of the current user. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity.
Use After Free in GitHub repository vim/vim prior to 9.0.0490. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
An issue was discovered in Bento4 through 1.6.0-639. 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 issue was discovered in Bento4 through 1.6.0-639. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Integer Overflow vulnerability could allow attackers to cause unexpected behavior through arithmetic overflow.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A Memory Allocation with Excessive Size Value vulnerablity in the TEE_Realloc function in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by invoking. 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.
The function tee_obj_free in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by invoking the function TEE_AllocateOperation with a disturbed heap. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A Buffer Access with Incorrect Length Value vulnerablity in the TEE_MACUpdate function in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by invoking. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.
A NULL pointer dereference issue in the TEE_MACCompareFinal function in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by invoking the function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A Buffer Access with Incorrect Length Value vulnerablity in the TEE_CipherUpdate function in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by invoking. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.
A Buffer Access with Incorrect Length Value vulnerablity in the TEE_MACComputeFinal function in Samsung mTower through 0.3.0 allows a trusted application to trigger a Denial of Service (DoS) by. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Buffer Overflow vulnerability could allow attackers to corrupt memory to execute arbitrary code or crash the application.
JasPer 3.0.6 allows denial of service via a reachable assertion in the function inttobits in libjasper/base/jas_image.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.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Integer Overflow vulnerability could allow attackers to cause unexpected behavior through arithmetic overflow.
TensorFlow is an open source platform for machine learning. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.