Improper neutralization of special elements used in an expression language statement ('Expression Language Injection') vulnerability in Apache Struts. If the application is configured to use the legacy RESTful action mapper, a crafted request can inject an OGNL expression that may lead to remote code execution. Struts 7 is affected only when the OGNL allowlist is disabled; it is enabled by default. Applications using the default action mapper, the restful2 mapper, or the Struts REST plugin are not affected.

This issue affects Apache Struts: from 2.0.0 through 2.3.37, from 2.5.0 through 2.5.33, from 6.0.0 through 6.11.0, from 7.0.0 through 7.3.0.

Users are recommended to upgrade to version 6.12.0 or 7.4.0, which fixes the issue.

An attacker can manipulate file upload params to enable paths traversal and under some circumstances this can lead to uploading a malicious file which can be used to perform Remote Code Execution. Users are recommended to upgrade to versions Struts 2.5.33 or Struts 6.3.0.2 or greater to fix this issue.