---
title: "CVE-2026-23903\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2026-23903?format=md
keywords: index, follow
---

# CVE-2026-23903

Publication date 9 February 2026

Last updated 2 September 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**5.3 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2026-23903?format=md#impact-score)

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## 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 2.1.0 and later has a new parameters to remediate this issue
shiro.ini: filterChainResolver.caseInsensitive = true
application.properties: shiro.caseInsensitive=true
Shiro 3.0.0 and later makes this the default in shiro.ini-based
configurations.
Shiro 3.0.1 and later makes this the default in all configurations,
including programmatic and Spring / Spring Boot.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| shiro | 26.04 LTS resolute | Needs evaluation |
| 25.10 questing | Ignored end of life, was needs-triage |
| 24.04 LTS noble | Needs evaluation |
| 22.04 LTS jammy | Needs evaluation |
| 20.04 LTS focal | Needs evaluation |
| 18.04 LTS bionic | Needs evaluation |
| 16.04 LTS xenial | Needs evaluation |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.3 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | Low |
  | Integrity impact | None |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.3 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-23903)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-23903)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-23903)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-23903)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-23903>
* <https://www.openwall.com/lists/oss-security/2026/02/08/1>
* <https://lists.apache.org/thread/5jjf0hnjcol58z2m5y255c7scz1lnp8k>
* <http://www.openwall.com/lists/oss-security/2026/02/08/1>