CVE-2026-56091: Apache Shiro: Authentication bypass in Guice-Web integration

[Lenny Primak <lprimak () apache org>]

Severity: 

Affected versions:

- Apache Shiro (org.apache.shiro:shiro-guice) through 2.99.99
- Apache Shiro (org.apache.shiro:shiro-guice) 3.0.0-alpha-0 through 3.0.0-alpha-1

Description:

When using Apache Shiro with the shiro-guice module in a web servlet context, a specially crafted HTTP request may 
cause an authentication bypass.
This vulnerability is similar to  https://www.cve.org/CVERecord?id=CVE-2020-1957 https://www.cve.org/CVERecord , except 
that it affects the `shiro-guice` module instead of the `shiro-spring` module.

This issue affects all Apache Shiro versions through 2.x, and 3.0.0-alpha-1 only when using `shiro-guice` module in a 
web servlet context.

Upgrade to version 3.0.0 or later, which fixes the issue.

Credit:

LocalHost <localhost.detect () gmail com> (finder)
Lenny Primak <lenny () flowlogix com> (remediation developer)

References:

https://shiro.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-56091