Apache Tomcat TOCTOU Race Condition Vulnerability

Published Date: December 18, 2024

Package Affected Versions Patched Versions Severity
📦 org.apache.tomcat:tomcat-catalina (Maven) >= 11.0.0-M1, < 11.0.2 11.0.2 High

Description

A high-severity vulnerability has been identified in Apache Tomcat. This issue, a Time-of-check Time-of-use (TOCTOU) race condition, arises during JSP compilation and can result in Remote Code Execution (RCE) on case-insensitive file systems. The vulnerability occurs when the default servlet is enabled for write—a non-default configuration.

Affected Versions



  • 11.0.0-M1 to 11.0.1

  • 10.1.0-M1 to 10.1.33

  • 9.0.0.M1 to 9.0.97


Patched Versions


The issue has been resolved in the following versions:

  • 11.0.2

  • 10.1.34

  • 9.0.98


Impact


This vulnerability exploits a timing discrepancy between the validation of a resource and its use during the JSP compilation process. If an attacker can manipulate the system within this brief window, they could execute arbitrary code remotely. The risk is significant, especially on systems configured with case-insensitive file systems and where the default servlet is writable. Notably, the vulnerable configuration is not enabled by default, reducing the potential attack surface.

Patches & Workarounds

Recommendations


Users should upgrade to the patched versions as soon as possible:

  • For the 11.x series: Upgrade to 11.0.2.

  • For the 10.1.x series: Upgrade to 10.1.34.

  • For the 9.0.x series: Upgrade to 9.0.98.


If upgrading is not immediately possible, consider mitigating the risk by disabling write access for the default servlet or using a case-sensitive file system.

References

https://tomcat.apache.org/security-10.html#Fixed_in_Apache_Tomcat_10.1.34

https://tomcat.apache.org/security-11.html#Fixed_in_Apache_Tomcat_11.0.2

https://tomcat.apache.org/security-9.html#Fixed_in_Apache_Tomcat_9.0.98

http://www.openwall.com/lists/oss-security/2024/12/17/4
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