CVE-2026-23901
Apache Shiro Affected by an Observable Timing Discrepancy Vulnerability
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.
How to fix CVE-2026-23901
To remediate CVE-2026-23901, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 2.1.0 or later
Is CVE-2026-23901 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- from 0, < 2.1.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |
| osv | CVSS 3.1 | LOW2.5 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N |