{"id":"CVE-2026-23901","state":"PUBLISHED","title":"Apache Shiro: Brute force attack possible to determine valid user names","description":"Observable Timing Discrepancy vulnerability in Apache Shiro.\n\nThis issue affects Apache Shiro: from 1.*, 2.* before 2.0.7.\n\nUsers are recommended to upgrade to version 2.0.7 or later, which fixes the issue.\n\nPrior to Shiro 2.0.7, code paths for non-existent vs. existing users are different enough,\nthat a brute-force attack may be able to tell, by timing the requests only, determine if\nthe request failed because of a non-existent user vs. wrong password.\n\nThe most likely attack vector is a local attack only.\nShiro security model  https://shiro.apache.org/security-model.html#username_enumeration  discusses this as well.\n\nTypically, brute force attack can be mitigated at the infrastructure 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