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)
Adobe Dimension versions 3.4.5 is 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.
Adobe Dimension versions 3.4.5 is 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.
Adobe Dimension versions 3.4.5 is 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.
Adobe Dimension versions 3.4.5 is 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.
Adobe Dimension versions 3.4.5 is 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.
Adobe Acrobat Reader versions 22.002.20212 (and earlier) and 20.005.30381 (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. No vendor patch available.
Adobe Acrobat Reader versions 22.002.20212 (and earlier) and 20.005.30381 (and earlier) are affected by a NULL Pointer Dereference vulnerability. Rated medium severity (CVSS 5.5), this vulnerability is no authentication required, low attack complexity.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In Music service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In Music service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In Music service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In Music service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In sensor driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In Gallery service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In camera driver, there is a possible memory corruption due to improper locking. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In messaging service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In music service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In cell service, there is a missing permission check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In gpu driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In face detect driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In face detect driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In camera driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
In jpg driver, there is a possible out of bounds write due to a missing bounds check. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. No vendor patch available.
A vulnerability found in jasper. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
A flaw was found In 389-ds-base. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
A vulnerability found in nss. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
A Regular expression denial of service (ReDoS) flaw was found in Function interpolateName in interpolateName.js in webpack loader-utils 2.0.0 via the url variable in interpolateName.js. 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.
Programs which compile regular expressions from untrusted sources may be vulnerable to memory exhaustion or denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
An attacker may cause a denial of service by crafting an Accept-Language header which ParseAcceptLanguage will take significant time to parse. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Reader.Read does not set a limit on the maximum size of file headers. 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.
Allocation of Resources Without Limits or Throttling in GitHub repository ikus060/rdiffweb prior to 2.5.0. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
In the Linux kernel 5.8 through 5.19.x before 5.19.16, local attackers able to inject WLAN frames into the mac80211 stack could cause a NULL pointer dereference denial-of-service attack against the. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. Public exploit code available.
A list management bug in BSS handling in the mac80211 stack in the Linux kernel 5.1 through 5.19.x before 5.19.16 could be used by local attackers (able to inject WLAN frames) to corrupt a linked. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. Public exploit code available.
A use-after-free in the mac80211 stack when parsing a multi-BSSID element in the Linux kernel 5.2 through 5.19.x before 5.19.16 could be used by attackers (able to inject WLAN frames) to crash the. Rated high severity (CVSS 8.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
Istio is an open platform-independent service mesh that provides traffic management, policy enforcement, and telemetry collection. 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 ikus060/rdiffweb prior to 2.5.0. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Tenda AC1200 US_AC6V2.0RTL_V15.03.06.51_multi_TDE01 was discovered to contain a buffer overflow in the 0x47ce00 function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda AC1900 AP500(US)_V1_180320(Beta) was discovered to contain a buffer overflow in the 0x32384 function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda AC1200 US_AC6V2.0RTL_V15.03.06.51_multi_TDE01 was discovered to contain a buffer overflow in the 0x4a12cc function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda AC1200 US_AC6V2.0RTL_V15.03.06.51_multi_TDE01 was discovered to contain a buffer overflow in the 0x47c5dc function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda AC1200 US_AC6V2.0RTL_V15.03.06.51_multi_TDE01 was discovered to contain a buffer overflow in the 0x47de1c function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Tenda AC1200 US_AC6V2.0RTL_V15.03.06.51_multi_TDE01 was discovered to contain a buffer overflow in the 0x475dc function. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A parsing issue with binary data in protobuf-java core and lite versions prior to 3.21.7, 3.20.3, 3.19.6 and 3.16.3 can lead to a denial of service attack. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Multiple Denial-of-Service (DoS) vulnerability was discovered in F-Secure & WithSecure products whereby the aerdl.dll unpacker handler function crashes. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
HashiCorp Nomad and Nomad Enterprise 1.0.2 up to 1.2.12, and 1.3.5 jobs submitted with an artifact stanza using invalid S3 or GCS URLs can be used to crash client agents. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
An issue in the fetch() method in the BasicProfile class of org.ini4j through version v0.5.4 allows attackers to cause a Denial of Service (DoS) via unspecified vectors. 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.
In addAutomaticZenRule of ZenModeHelper.java, there is a possible permanent degradation of performance due to resource exhaustion. Rated medium severity (CVSS 5.5), this vulnerability is low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
In binder_inc_ref_for_node of binder.c, there is a possible way to corrupt memory due to a use after free. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity.
In io_identity_cow of io_uring.c, there is a possible way to corrupt memory due to a use after free. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity.
Windows Secure Channel Denial of Service Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Internet Key Exchange (IKE) Protocol Denial of Service Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Windows Local Session Manager (LSM) Denial of Service Vulnerability. Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity.
Windows Event Logging Service Denial of Service Vulnerability. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable, low attack complexity.
Local Security Authority Subsystem Service (LSASS) Denial of Service Vulnerability. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
Windows Local Session Manager (LSM) Denial of Service Vulnerability. Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity.
Windows Point-to-Point Tunneling Protocol Denial of Service Vulnerability. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required.
A Regular expression denial of service (ReDoS) flaw was found in Function interpolateName in interpolateName.js in webpack loader-utils 2.0.0 via the resourcePath variable in interpolateName.js. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Windows TCP/IP Driver Denial of Service Vulnerability. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
OpenSSL supports creating a custom cipher via the legacy EVP_CIPHER_meth_new() function and associated function calls. 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.
Traefik (pronounced traffic) is a modern HTTP reverse proxy and load balancer that assists in deploying microservices. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
XAPI open file limit DoS It is possible for an unauthenticated client on the network to cause XAPI to hit its file-descriptor limit. Rated medium severity (CVSS 5.3), 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.
A vulnerability has been identified in SICAM P850 (7KG8500-0AA00-0AA0) (All versions < V3.10), SICAM P850 (7KG8500-0AA00-2AA0) (All versions < V3.10), SICAM P850 (7KG8500-0AA10-0AA0) (All versions <. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, low attack complexity.
A vulnerability has been identified in SIMATIC HMI Comfort Panels (incl. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A vulnerability has been identified in Desigo PXM30-1 (All versions < V02.20.126.11-41), Desigo PXM30.E (All versions < V02.20.126.11-41), Desigo PXM40-1 (All versions < V02.20.126.11-41), Desigo. Rated high severity (CVSS 8.3), this vulnerability is remotely exploitable, low attack complexity.
A vulnerability has been identified in APOGEE MBC (PPC) (BACnet) (All versions), APOGEE MBC (PPC) (P2 Ethernet) (All versions), APOGEE MEC (PPC) (BACnet) (All versions), APOGEE MEC (PPC) (P2. Rated high severity (CVSS 8.7), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.
A vulnerability has been identified in RUGGEDCOM RM1224 LTE(4G) EU (6GK6108-4AM00-2BA2) (All versions < V7.1.2), RUGGEDCOM RM1224 LTE(4G) NAM (6GK6108-4AM00-2DA2) (All versions < V7.1.2), SCALANCE. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
The aeson library is not safe to use to consume untrusted JSON input. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
fastify is a fast and low overhead web framework, for Node.js. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.
Azure RTOS USBx is a USB host, device, and on-the-go (OTG) embedded stack, fully integrated with Azure RTOS ThreadX and available for all Azure RTOS ThreadX-supported processors. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
Dell Wyse ThinOS 2205 contains a Regular Expression Denial of Service Vulnerability in UI. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity.
A vulnerability in the implementation of IPv6 VPN over MPLS (6VPE) with Zone-Based Firewall (ZBFW) of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of. Rated high severity (CVSS 7.4), this vulnerability is no authentication required, low attack complexity. No vendor patch available.
A vulnerability in the egress MPLS packet processing function of Cisco IOS XE Software for Cisco Catalyst 3650, Catalyst 3850, and Catalyst 9000 Family Switches could allow an unauthenticated, remote. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A vulnerability in the DNS application layer gateway (ALG) functionality that is used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
An issue was discovered in D-Bus before 1.12.24, 1.13.x and 1.14.x before 1.14.4, and 1.15.x before 1.15.2. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
An issue was discovered in D-Bus before 1.12.24, 1.13.x and 1.14.x before 1.14.4, and 1.15.x before 1.15.2. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
An issue was discovered in D-Bus before 1.12.24, 1.13.x and 1.14.x before 1.14.4, and 1.15.x before 1.15.2. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available.
fat_free_crm is a an open source, Ruby on Rails customer relationship management platform (CRM). Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity.
VMware ESXi contains a null-pointer deference vulnerability. Rated medium severity (CVSS 6.5), this vulnerability is low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
In ril, there is a possible system crash due to an incorrect bounds check. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In wlan, there is a possible use after free due to an incorrect status check. Rated medium severity (CVSS 6.7), this vulnerability is low attack complexity. No vendor patch available.
In Wi-Fi driver, there is a possible way to disconnect Wi-Fi due to an improper resource release. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
In vdec fmt, 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.