CVE-2024-56337 – TOCTOU race condition in Apache Tomcat

Abstract

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.0.97. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other, older, EOL versions may also be affected. The mitigation for CVE-2024-50379 was incomplete. Users running Tomcat on a case insensitive file system with the default servlet write enabled (readonly initialisation parameter set to the non-default value of false) may need additional configuration to fully mitigate CVE-2024-50379 depending on which version of Java they are using with Tomcat: - running on Java 8 or Java 11: the system property sun.io.useCanonCaches must be explicitly set to false (it defaults to true) - running on Java 17: the system property sun.io.useCanonCaches, if set, must be set to false (it defaults to false) - running on Java 21 onwards: no further configuration is required (the system property and the problematic cache have been removed) Tomcat 11.0.3, 10.1.35 and 9.0.99 onwards will include checks that sun.io.useCanonCaches is set appropriately before allowing the default servlet to be write enabled on a case insensitive file system. Tomcat will also set sun.io.useCanonCaches to false by default where it can.

The Oxygen products incorporate Apache Tomcat as a third-party component. This advisory was opened to address the potential impact of this third-party component vulnerability.

Affected Products/Versions

Mitigation

None

Detail

CVE-2024-56337

Severity: Critical

CVSS Score: 9.8

A time-of-check to time-of-use (TOCTOU) race condition in Apache Tomcat may allow unintended write access when specific preconditions are met. The issue is an incomplete mitigation for CVE-2024-50379 and affects Tomcat versions 11.0.0-M1 through 11.0.1, 10.1.0-M1 through 10.1.33, and 9.0.0.M1 through 9.0.97. Exploitation requires running on a case-insensitive filesystem and enabling the default servlet for writes (readonly=false). Depending on the Java version, additional configuration may be required to fully mitigate CVE-2024-50379; Tomcat 11.0.3, 10.1.35, and 9.0.99 include additional checks and defaults that address this condition.

Based on our review, the vulnerability is not exploitable in supported, default deployments of the affected Oxygen products because they run on case-sensitive filesystems and do not enable the Tomcat default servlet for writes (readonly remains true).