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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2022.1599 CVE-2021-31805: Apache Struts: Forced OGNL evaluation, when evaluated on raw not validated user input in tag attributes, may lead to RCE 13 April 2022 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Apache Struts Publisher: Apache Operating System: Windows UNIX variants (UNIX, Linux, OSX) Resolution: Patch/Upgrade CVE Names: CVE-2021-31805 Original Bulletin: https://cwiki.apache.org/confluence/display/WW/S2-062 Comment: CVSS (Max): None available when published - --------------------------BEGIN INCLUDED TEXT-------------------- Summary Forced OGNL evaluation, when evaluated on raw not validated user input in tag attributes, may lead to remote code execution - same as S2-061. Who should read this All Struts 2 developers and users Impact of vulnerability Possible Remote Code Execution vulnerability Maximum security rating Important Recommendation Upgrade to Struts 2.5.30 or greater Affected Software Struts 2.0.0 - Struts 2.5.29 Reporters Chris McCown CVE Identifier CVE-2021-31805 Problem The fix issued for CVE-2020-17530 (S2-061) was incomplete. 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. Solution Avoid using forced OGNL evaluation on untrusted user input, and/or upgrade to Struts 2.5.30 or greater which checks if expression evaluation won't lead to the double evaluation. DISCLAIMER Struts won't accept double evaluation issues caused by not validated end-user input (owing to developer error) anymore as vulnerability. We accepted this one as vulnerability because it's about an error in our previously accepted vulnerability. We welcome and appreciate reports in this regard to minimize developer error effect albeit! Backward compatibility No issues expected when upgrading to Struts 2.5.30 Workaround Do not use forced OGNL evaluation in the tag's attributes based on untrusted/ unvalidated user input, please follow out recommendations from the Security Guide. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. 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If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBYlY8bONLKJtyKPYoAQgcOhAAl+rUHWJCdMGzdMV+Q2NY5PFrPlfSnzQt kq9/JVwrniFMUp5foAV1VqrAVS2SMt62qNKmXmGvbcbP4K9ypuxdqGzlnCcxW/9T mEztJqJFv8gHDZXe6nBjau7CgPbS/dUYMXRQRXM0JjA05NJDhZurLd0lWFYhJgQo AM7e2dYZDPBpr05C8pwhn6oHAyf33Do7nJBGM1YZmDTc8oWTpxug78I5I9mPsjtw m266jljx8KLJYIb/0HhbpCnyV0m4FXJm+tiGZXqnB8lalMfXC2muLjrISeVnaaOV xdt5whpeV0XcQO/fIdyumoPKxk0p5AcpW6rRHYT8/8uX44JwYJXgQet4K6tVJsyL pYRbXHKgjerE8jkSuj9qz4hCz5qKsSVB8O4dwZrvMhBmK92hJb7Qm6b4SGPv1b+I AGBFqPGspfFgaP9OK2fhviI7ZD8zNTqGUoYkAzOnqWYPosdmcqTeSD/qorfPXYKu fGJOQtq2aXmEvywwuBfOYWHCd/NYzfeVLnZ/5NVo2hIr2jfzcK6nlYuaR5n/kLNw Fn/oJUMxRHSRFCCf3rDY3UrDGbv8fGHM6aXxs6E6MaePl6+LEMfhhZ43GZXumGTm tG3JWuzAW/OjKkPKXOYCYlUaMizFDQ3826ZIcbFR0gpvq1mg5FzBx4rMGBlcT+eF esGM9UE5mcA= =tr7Q -----END PGP SIGNATURE-----