Apache Tomcat versions 8.5.0 to 8.5.66, 9.0.0.M1 to 9.0.46, and 10.0.0-M1 to 10.0.6 did not correctly parse the HTTP transfer-encoding request header in certain circumstances, leading to the possibility of request smuggling when used in conjunction with a reverse proxy. This vulnerability allows attackers to exploit the handling of transfer encoding by Tomcat under specific conditions.
The severity of this vulnerability is classified as medium, with a CVSS score of 5.3. This score indicates a moderate risk level, primarily due to the potential for integrity impacts. Organizations utilizing the affected versions must prioritize patching to mitigate the risk of exploitation.
Risk to organizations includes potential unauthorized access and integrity issues due to incorrect parsing of headers. This can lead to significant security incidents if exploited. Thus, timely remediation is essential.
Organizations should prioritize patching immediately, as no confirmed public exploits have been found at this time. However, the vulnerability remains a concern, necessitating swift action.
Vulnerability Details
The vulnerability affects Apache Tomcat versions ranging from 8.5.0 to 8.5.66, 9.0.0.M1 to 9.0.46, and 10.0.0-M1 to 10.0.6. It was officially published on July 12, 2021.
The root cause stems from the mismanagement of HTTP transfer-encoding headers, especially when the client specifies acceptance of an HTTP/1.0 response. Tomcat also incorrectly honored the identity encoding and failed to validate the chunked encoding as the final encoding, leading to potential exploitation.
The CWE classification for this vulnerability is CWE-444, indicating a failure to properly parse requests. This oversight can result in application-level vulnerabilities, especially in environments using reverse proxies.
Technical Analysis
The attack vector for this vulnerability is network-based, requiring no privileges or user interaction, making it accessible for potential attackers. The complexity of the attack is low, meaning that attackers can exploit this vulnerability with minimal effort.
The vulnerability primarily affects the integrity of the system, as successful exploitation can allow unauthorized modifications to data. However, it does not impact the confidentiality or availability of the system.
Risk & Impact Analysis
Real-world deployment risk associated with CVE-2021-33037 includes potential data integrity issues and unauthorized access, especially for organizations relying on Apache Tomcat in critical applications. The blast radius can be significant, impacting all applications utilizing the affected Tomcat versions.
Organizations should address this vulnerability in their priority patch cycle, given the moderate CVSS score and potential exploitation scenarios.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Apache Tomcat are 10.0.0-M1 to 10.0.6, 9.0.0.M1 to 9.0.46, and 8.5.0 to 8.5.66. Organizations using these versions should update to the latest patched versions as soon as possible.
Mitigation & Remediation
Organizations should patch to the latest version of Apache Tomcat to remediate this vulnerability. Additionally, configuration hardening should be reviewed to ensure security best practices are followed.
For further guidance, organizations can refer to the penetration testing services offered by AppSecure to validate the effectiveness of their patching strategy.
Detection Guidance
To detect potential exploitation attempts, organizations should monitor logs for unusual HTTP requests involving transfer-encoding headers. Additionally, behavioral anomalies should be analyzed to identify any deviations from normal traffic patterns.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-33037 lies in its demonstration of how mismanagement of HTTP headers can lead to serious vulnerabilities, such as request smuggling. This pattern highlights the need for continuous monitoring and updating of security practices in application development.
The incident serves as a reminder for security teams to conduct regular assessments and implement robust security measures. Organizations should consider engaging in proactive security testing strategies, such as red teaming to identify and remediate potential vulnerabilities before they can be exploited.
In conclusion, CVE-2021-33037 highlights critical vulnerabilities in widely used software, necessitating swift action to mitigate risks and protect sensitive data.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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