CVE-2026-23901

Name	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1127944

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
shiro (PTS)	bullseye	1.3.2-4+deb11u1	vulnerable
	bookworm	1.3.2-5	vulnerable
	sid, trixie	1.3.2-6	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
shiro	source	(unstable)	(unfixed)			1127944

Notes

[trixie] - shiro <no-dsa> (Minor issue)
[bookworm] - shiro <no-dsa> (Minor issue)
[bullseye] - shiro <postponed> (Minor issue)
https://www.openwall.com/lists/oss-security/2026/02/08/2