CVE-2026-23903: Apache Shiro: Auth bypass when accessing static files only on case-insensitive filesystems

[Lenny Primak <lprimak () apache org>]

Severity: low 

Affected versions:

- Apache Shiro (org.apache.shiro:shiro-web) before 2.0.7

Description:

Authentication Bypass by Alternate Name vulnerability in Apache Shiro.

This issue affects Apache Shiro: before 2.0.7.

Users are recommended to upgrade to version 2.0.7, which fixes the issue.

The issue only effects static files. If static files are served from a case-insensitive filesystem,
such as default macOS setup, static files may be accessed by varying the case of the filename in the request.
If only lower-case (common default) filters are present in Shiro, they may be bypassed this way.

Shiro 2.0.7 and later has a new parameters to remediate this issue
shiro.ini: filterChainResolver.caseInsensitive = true
application.propertie: shiro.caseInsensitive=true

Shiro 3.0.0 and later (upcoming) makes this the default.

Credit:

Jesse Yang (finder)
Lenny Pimak (remediation developer)

References:

https://shiro.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-23903