---
title: "CVE-2026-23901\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-2026-23901?format=md
keywords: index, follow
---

# CVE-2026-23901

Publication date 10 February 2026

Last updated 10 July 2026

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**2.5 · Low**

[Score breakdown](https://ubuntu.com/security/CVE-2026-23901?format=md#impact-score)

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## 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.

## 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 v4.0

[CVSS v4.0](https://ubuntu.com/security/CVE-2026-23901?format=md)
[CVSS v3.0](https://ubuntu.com/security/CVE-2026-23901?format=md)

**Base score**

1.0 · Low

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | High |
  | Attack requirements | Present |
  | Privileges required | Low |
  | User interaction | Active |
  | Vulnerable system - Confidentiality impact | Low |
  | Vulnerable system - Integrity impact | None |
  | Vulnerable system - Availability impact | None |
  | Subsequent system - Confidentiality impact | Low |
  | Subsequent system - Integrity impact | None |
  | Subsequent system - Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 1.0 · Low |
  | Base + Threat score | - |
  | Base + Environmental score | - |
  | Base + Threat + Environmental score | - |

**Vector:** CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:A/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/S:N/AU:Y/R:A/V:C/RE:L/U:Green

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-23901)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-23901)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-23901)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-23901)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-23901>
* <https://www.openwall.com/lists/oss-security/2026/02/08/2>