title: Forced OGNL evaluation, when evaluated on raw not validated user input in tag attributes, may lead to RCE.
description: The fix issued for CVE-2020-17530 was incomplete. So from Apache Struts 2.0.0 to 2.5.29, still some of the tag’s attributes could perform a double evaluation if a developer applied forced OGNL evaluation by using the %{...} syntax. Using forced OGNL evaluation on untrusted user input can lead to a Remote Code Execution and security degradation.
problem types: CWE-917 Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
affected:
{
product: Apache Struts
vendor: Apache Software Foundation
versions:
status: affected, version: 2.0.0 to 2.5.29
}
workarounds: Avoid using forced OGNL evaluation on untrusted user input, and/or upgrade to Struts 2.5.30 which checks if expression evaluation won’t lead to the double evaluation.
Please read our Security Bulletin S2-062 for more details.