Bug 2438436 (CVE-2026-23901)

Summary:	CVE-2026-23901 org.apache.shiro/shiro-core: Apache Shiro: Brute force attack possible to determine valid user names
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	asoldano, bbaranow, bmaxwell, brian.stansberry, darran.lofthouse, dosoudil, fmariani, gmalinko, istudens, ivassile, iweiss, janstey, mosmerov, msvehla, nwallace, pberan, pdelbell, pesilva, pjindal, pmackay, rstancel, rstepani, smaestri, tcunning, tom.jenkinson, yfang
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	An Observable Timing Discrepancy vulnerability has been discovered 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.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-02-10 10:01:13 UTC

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.