CVE-2026-23901
Apache Shiro: Brute force attack possible to determine valid user names
- State
- Published
- Severity
- 1.0 Low
- Published
- Feb 10, 2026
- Updated
- Feb 10, 2026
- Reserved
- Jan 17, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 1.0 Low | CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:A/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/S:N/AU:Y/R:A/V:C/RE:L/U:Green | apache |
Weaknesses
- CWE-208 Observable Timing Discrepancy
Affected Products
| Product | Versions |
|---|---|
Apache ShiroApache Software Foundation |
|
References
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