This vulnerability allows the exploitation of a concurrency bug in Apache Tomcat that could result in client connections sharing an instance of Http11Processor. Specifically, this issue affects Apache Tomcat versions 10.1.0 to 10.1.0-M12, 10.0.0-M1 to 10.0.18, 9.0.0-M1 to 9.0.60, and 8.5.0 to 8.5.77. The bug is hard to trigger but poses a risk of incorrect responses being sent to clients.
The CVSS score for this vulnerability is 3.7, indicating a low severity level. Even though the exploitability score is low, the potential for information disclosure warrants attention.
Risk to organizations includes potential exposure of sensitive information through misrouted responses, which can occur under specific conditions. Given the complexity of triggering this vulnerability, immediate exploitation is not expected, but organizations are urged to monitor for any unusual behavior.
Organizations should address this vulnerability in their priority patch cycle. Patching is essential to ensure that systems are secured against this potential exposure.
Vulnerability Details
The simplified implementation of blocking reads and writes introduced in Tomcat 10 and back-ported to Tomcat 9.0.47 onwards exposed a long-standing concurrency bug. When this vulnerability is exploited, it could cause client connections to share an Http11Processor instance, resulting in responses, or part responses, being received by the wrong client.
The CVSS score of 3.7 indicates a low-severity vulnerability, characterized by a high attack complexity and no privileges required, nor user interaction necessary. The confidentiality impact is low, while integrity and availability impacts are none.
Technical Analysis
The root cause of this vulnerability stems from the changes made in the implementation of blocking reads and writes. The attack vector is network-based, and the attack complexity is high, indicating that specific conditions must be met for exploitation. Importantly, no privileges are required to exploit this vulnerability, and no user interaction is necessary.
The confidentiality impact is assessed as low, meaning that while sensitive data might be exposed, the risk is relatively contained. There is no impact on integrity or availability.
Risk & Impact Analysis
Real-world deployment risk is present, albeit limited, due to the complexity of triggering this vulnerability. Nevertheless, organizations that deploy affected versions of Tomcat should be aware of the potential for sensitive data exposure through misrouted responses.
The blast radius is primarily significant for organizations that handle sensitive client data. Therefore, organizations should prioritize addressing this vulnerability during their patch cycles.
Given the low CVSS score and the absence of known exploitation in the wild, organizations have some leeway in scheduling remediation. However, it is advisable to monitor for updates from the Apache Software Foundation and maintain awareness of any developments regarding this vulnerability.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of Apache Tomcat are affected by this vulnerability: 10.1.0 to 10.1.0-M12, 10.0.0-M1 to 10.0.18, 9.0.0-M1 to 9.0.60, and 8.5.0 to 8.5.77. All versions prior to vendor patch are vulnerable.
Mitigation & Remediation
Organizations should prioritize patching immediately by updating to the latest version of Apache Tomcat. If patches are not available, consider implementing configuration hardening measures to mitigate the risks associated with this vulnerability.
Monitoring for unusual behavior in client connections can also help detect potential exploitation attempts. For detailed guidance, organizations can refer to the penetration testing services offered by AppSecure.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor logs for unusual connection patterns and check for any behavioral anomalies in client responses. Network signatures related to Apache Tomcat should also be reviewed.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-43980 lies in the concurrency issues that are often overlooked in modern applications. This vulnerability serves as a reminder for security teams to conduct thorough code reviews and testing, especially when implementing new features.
Organizations should also consider engaging in regular security assessments to identify similar vulnerabilities before they can be exploited. For more information on security best practices, refer to the penetration testing methodology and other security resources provided by AppSecure.
As we observe the evolving landscape of vulnerabilities, it is crucial for organizations to stay informed and proactive in their security posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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