CVE-2026-23901

Description

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.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://nvd.nist.gov/vuln/detail/CVE-2026-23901
• https://github.com/apache/shiro
• https://lists.apache.org/thread/mm1jct9b86jvnh3y44tj22xvjtx3xhhh
• http://www.openwall.com/lists/oss-security/2026/02/08/2
• https://security-tracker.debian.org/tracker/CVE-2026-23901