CVE-2026-23901 – Apache Shiro: Brute force attack possible to determine valid user names

CVE ID : CVE-2026-23901

Published : Feb. 10, 2026, 10:15 a.m. | 2 hours, 5 minutes ago

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.

Severity: 1.0 | LOW

Visit the link for more details, such as CVSS details, affected products, timeline, and more…