CVE-2021-31805 Forced OGNL evaluation, when evaluated on raw not validated user input in tag attributes, may lead to RCE.

What is CVE-2021-31805?

CVE-2021-31805 is a critical code injection vulnerability in Apache Struts, published on 12 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-917

Which versions are affected by CVE-2021-31805?

2 open source packages ship an affected version, including org.apache.struts:struts2-core. It affects 1 product.

Products include Apache Struts.

How do I fix CVE-2021-31805?

Upgrade org.apache.struts:struts2-core to 2.5.30 or later.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2021-31805 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-31805 exists.

Public exploit code: 1 Nuclei template and 8 proofs of concept on GitHub.

Other vulnerabilities in Apache Struts

• CVE-2020-17530 Apache Struts Remote Code Execution Exploited Critical 9.8
• CVE-2017-9791 Apache Struts 1 Improper Input Validation Exploited Critical 9.8
• CVE-2017-5638 Apache Struts Remote Code Execution Exploited Critical 9.8
• CVE-2012-0391 Apache Struts 2 Improper Input Validation Exploited Critical 9.8
• CVE-2018-11776 Apache Struts Remote Code Execution Exploited High 8.1

All Apache Struts vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-v8j6-6c2r-r27c.