CVE-2026-23901: Apache Shiro

Low severity, CVSS 2.5. EPSS: 0.2% chance of exploitation in the next 30 days.

Observable Timing Discrepancy vulnerability in Apache Shiro. This issue affects Apache Shiro: from 1.*, 2.* before 2.0.7. Users are recommended to upgrade to version 2.0.7 or later, which fixes the issue. Prior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough, that a brute-force attack may be able to tell, by timing the requests only, determine if the request failed because of a non-existent user vs. wrong password. The most likely attack vector is a local attack only. Shiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well. Typically, brute force attack can be mitigated at the infrastructure level.

Affected products

• Apache Shiro: before 2.0.7 (fixed in 2.0.7)

Published 2026-02-10. Last modified 2026-06-17.