CVE-2026-23901

Summary

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 Software

Weaknesses

• CWE-208: CWE-208 Observable Timing Discrepancy

ADP Enrichment

CVE Program Container

Additional References

• http://www.openwall.com/lists/oss-security/2026/02/08/2

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://lists.apache.org/thread/mm1jct9b86jvnh3y44tj22xvjtx3xhhh

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