CVE-2026-23901
Publication date 10 February 2026
Last updated 10 July 2026
Ubuntu priority
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
| Package | Ubuntu Release | Status |
|---|---|---|
| shiro | 26.04 LTS resolute |
Needs evaluation
|
| 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 | Ignored end of ESM support, was needs-triage |
Severity score breakdown
CVSS version:
Base score
1.0 · Low
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
Base score
2.5 · Low
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N