CVE-2022-21716 is a high-severity vulnerability found in the Twisted framework, which is an event-based framework for internet applications that supports Python 3.6 and later. The vulnerability allows the Twisted SSH client and server implementation to accept an infinite amount of data for the peer's SSH version identifier, leading to excessive memory usage and potential denial of service (DoS) conditions.
The CVSS score for this vulnerability is 7.5, indicating a high severity level. The vulnerability's impact on availability is significant, as it can lead to system crashes or unavailability due to memory exhaustion. With the exploitability score measured at 3.9, organizations should prioritize remediation efforts.
Currently, there are no known workarounds for this vulnerability. The only solution is to upgrade to Twisted version 22.2.0 or later, where a patch has been released. Organizations using affected versions of Twisted must act swiftly to mitigate potential risks.
Risk to organizations includes the potential for a denial of service, which could disrupt services relying on the Twisted framework. Given the wide usage of Twisted in various applications, the impact of this vulnerability could be extensive.
Vulnerability Details
The official description notes that prior to version 22.2.0, Twisted allows an infinite amount of data to be accepted for the peer's SSH version identifier. This behavior can be exploited by sending a crafted SSH request, leading to a significant memory overflow. The vulnerability is classified under CWE-120 and CWE-770.
The vulnerability affects the following products and vendors: Twisted, Debian Linux, Fedora, and Oracle HTTP Server. The affected versions include Twisted versions prior to 22.2.0, Debian Linux 9.0, Fedora 35 and 36, and Oracle HTTP Server versions 12.2.1.3.0 and 12.2.1.4.0.
Technical Analysis
The root cause of CVE-2022-21716 is the flawed handling of incoming data by the Twisted SSH implementation, which does not enforce limits on the amount of data that can be accepted for the SSH version identifier. This results in a buffer overflow that consumes all available memory, leading to system instability.
The attack vector is network-based, meaning an attacker can exploit this vulnerability remotely without requiring physical access. The complexity of the attack is low, as it does not require any special conditions or privileges to exploit. Furthermore, there is no user interaction needed, which makes this vulnerability particularly dangerous.
In terms of impacts, the vulnerability affects availability significantly, as it can crash the application or the server hosting the application. However, there are no confidentiality or integrity impacts associated with this vulnerability.
Risk & Impact Analysis
Organizations utilizing Twisted in their applications face a substantial risk if they do not address this vulnerability. The potential for denial of service can lead to significant disruptions in service availability, particularly for mission-critical applications.
The blast radius is considerable given Twisted's utilization in various environments, including web servers, application servers, and other network services. As the vulnerability affects multiple distributions and versions, organizations must assess their exposure and prioritize mitigation efforts.
Organizations should prioritize patching immediately. The exploitability score indicates a high potential for successful attacks, emphasizing the urgency for remediation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions are affected by CVE-2022-21716: Twisted versions prior to 22.2.0, Debian Linux 9.0, Fedora 35, Fedora 36, and Oracle HTTP Server versions 12.2.1.3.0 and 12.2.1.4.0. Organizations using any of these versions should upgrade to the patched version immediately.
Mitigation & Remediation
Organizations should upgrade to Twisted version 22.2.0, where the vulnerability is patched. In addition to upgrading, organizations can implement network controls to limit access to the SSH service and monitor for suspicious traffic patterns. Regular security assessments and penetration testing can further enhance security posture.
For comprehensive vulnerability management, organizations may consider conducting penetration testing to identify similar weaknesses and validate remediation effectiveness.
Detection Guidance
Organizations should monitor logs for any unusual activity related to SSH connections. Behavioral anomalies, such as unexpected spikes in memory usage or unusual SSH connection attempts, should be flagged for further investigation. Network signatures indicating excessive data transfer during SSH handshakes can also serve as indicators of exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2022-21716 lies in its demonstration of the vulnerabilities associated with network protocols and their implementations. The incident highlights the importance of rigorous testing and validation in software development, particularly for libraries that serve as foundational components in many applications.
Security teams should note the trend of increasing vulnerabilities in widely used frameworks, emphasizing the need for proactive vulnerability management practices. Regularly updating dependencies and conducting thorough security audits are essential strategies to mitigate risk.
For further insights into vulnerability management, organizations can explore best practices through our vulnerability management program, or consider our penetration testing methodology for a comprehensive understanding of security testing practices.
Known Exploitation Timeline
This CVE has not been included in the Known Exploited Vulnerabilities (KEV) catalog, indicating that there are no known active exploitation events reported as of now.
EPSS Risk Context
The EPSS score for CVE-2022-21716 is 0.01238, placing it in the 79.24 percentile. This indicates a low probability of exploitation, but organizations should remain vigilant and prioritize patching this vulnerability due to its high potential impact.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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