CVE-2026-23901 — shiro-core
LOWCVE-2026-23901 is a low-severity (CVSS 2.5) CWE-208 vulnerability in org.apache.shiro:shiro-core. A fix is available for org.apache.shiro:shiro-core — see the affected versions and patch details below.
Apache Shiro Affected by an Observable Timing Discrepancy Vulnerability
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-23901.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.apache.shiro:shiro-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.shiro:shiro-core | all versions | 2.1.0org.apache.shiro:shiro-core:2.1.0 |
Affected Products
shiroapacheDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.shiro:shiro-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.shiro:shiro-core to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23901 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2026-23901 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-23901 in your dependencies?
Find it across Maven, including transitive dependencies.