Summary
Apache Shiro Affected by an Observable Timing Discrepancy Vulnerability
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.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-23901? CVE-2026-23901 is a low-severity security vulnerability in org.apache.shiro:shiro-core (maven), affecting versions < 2.1.0. It is fixed in 2.1.0.
- Which versions of org.apache.shiro:shiro-core are affected by CVE-2026-23901? org.apache.shiro:shiro-core (maven) versions < 2.1.0 is affected.
- Is there a fix for CVE-2026-23901? Yes. CVE-2026-23901 is fixed in 2.1.0. Upgrade to this version or later.
- Is CVE-2026-23901 exploitable, and should I be worried? Whether CVE-2026-23901 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-23901 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-23901? Upgrade
org.apache.shiro:shiro-coreto 2.1.0 or later.