This vulnerability allows excessive CPU usage due to unbounded reading of HTTP/2 CONTINUATION frames in the nghttp2 library. It affects versions prior to 1.61.0, causing significant performance degradation on affected systems. Organizations using Debian or Fedora platforms are at risk, with the potential for denial-of-service conditions.
With a CVSS score of 5.3, this vulnerability is classified as medium severity. Organizations should prioritize patching immediately as the impact on system performance could be substantial if exploited.
The vulnerability is actively exploitable, and while a public proof of concept exists, no known exploits have been confirmed in the wild. However, organizations should not underestimate the risk to their infrastructure, especially in production environments.
Patching to nghttp2 version 1.61.0 or later is crucial as it mitigates this vulnerability by limiting the number of CONTINUATION frames accepted per stream. There are no known workarounds for this issue.
Organizations should remain vigilant and monitor for any unusual CPU usage patterns that may indicate exploitation attempts.
Vulnerability Details
nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. The nghttp2 library prior to version 1.61.0 keeps reading the unbounded number of HTTP/2 CONTINUATION frames even after a stream is reset to keep HPACK context in sync. This causes excessive CPU usage to decode HPACK stream. nghttp2 v1.61.0 mitigates this vulnerability by limiting the number of CONTINUATION frames it accepts per stream. There is no workaround for this vulnerability.
The CVSS score for this vulnerability is 5.3, indicating a medium severity level. The attack vector is classified as NETWORK, with a low attack complexity. No privileges are required, and user interaction is not necessary. The impact on availability is low, while there is no impact on confidentiality or integrity.
Technical Analysis
The root cause of this vulnerability lies in the handling of HTTP/2 CONTINUATION frames. When a stream is reset, the library continues to process these frames without boundaries, leading to an unbounded increase in CPU usage as it attempts to decode the HPACK stream. The attack vector is network-based, meaning that an attacker can exploit this vulnerability remotely.
Attack complexity is low, as no special conditions are required to exploit the vulnerability. Additionally, no privileges are required, and no user interaction is necessary for exploitation. This makes the vulnerability particularly concerning for organizations utilizing affected versions of nghttp2.
The impacts on confidentiality and integrity are none; however, the availability is at risk due to the potential for denial-of-service conditions from excessive CPU usage.
Risk & Impact Analysis
Risk to organizations includes the possibility of degraded performance and denial-of-service conditions due to excessive CPU consumption. Affected organizations may experience system outages or sluggishness, impacting user experience and operational efficiency.
The blast radius for this vulnerability is significant, especially for large-scale deployments of nghttp2. Organizations that rely on this library for handling HTTP/2 traffic should prioritize remediation to avoid disruptions.
Given the medium severity rating and active exploitability, organizations should assess their exposure and prioritize patching as part of their routine security maintenance.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Affected versions include nghttp2 prior to 1.61.0, Debian Linux versions 10.0 and 11.0, and Fedora versions 38, 39, and 40. Organizations using these versions should upgrade to mitigate the vulnerability.
Mitigation & Remediation
Organizations should upgrade to nghttp2 version 1.61.0 or later. If immediate patching is not possible, consider implementing network controls to limit access to affected services. Monitoring should be enhanced to detect unusual CPU usage patterns that may indicate attempts to exploit this vulnerability. Further details on patching can be found through penetration testing to ensure all vulnerabilities are addressed.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor system logs for indicators of excessive CPU usage related to nghttp2 processing. Look for behavioral anomalies that indicate potential abuse of HTTP/2 CONTINUATION frames. Additionally, network signatures that reflect abnormal traffic patterns can help identify potential exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability highlights the risks associated with unbounded resource consumption in network protocols. Organizations should consider adopting a proactive approach to vulnerability management by implementing a vulnerability management program that prioritizes timely updates and threat intelligence integration.
This incident is a reminder of the importance of rigorous security testing, such as penetration testing methodology to identify similar weaknesses before they can be exploited.
Security teams should remain vigilant and continuously assess their systems for potential vulnerabilities, incorporating strategies for rapid response to emerging threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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