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Apache Shiro has an Authentication Bypass

Moderate severity GitHub Reviewed Published Feb 9, 2026 to the GitHub Advisory Database • Updated Feb 11, 2026

Package

maven org.apache.shiro:shiro-spring (Maven)

Affected versions

<= 2.0.6

Patched versions

2.1.0

Description

Impact

Authentication Bypass:
A vulnerability exists in Apache Shiro that allows authentication bypass for static files when served from a case-insensitive filesystem (such as the default configuration on macOS or Windows).

The issue arises when Shiro's URL filters are configured with lower-case rules (a common default), but the underlying operating system treats mixed-case filenames as identical. An attacker can access protected static resources by varying the capitalization of the filename in the request (e.g., requesting /SECRET.TXT to bypass a rule for /secret.txt).

This issue specifically affects static file handling and does not impact dynamic resource paths that are case-sensitive.

Patches

Users should upgrade to Apache Shiro 2.1.0 or later.

Important Configuration Note:
Version 2.1.0 introduces a new configuration parameter to handle case-insensitivity, which must be enabled manually to resolve the issue:

  • shiro.ini: 
    filterChainResolver.caseInsensitive = true
  • Spring Boot (application.properties): 
    shiro.caseInsensitive=true

Note: Apache Shiro 3.0.0 (upcoming) will enable this setting by default.

Workarounds

  • Ensure that the filesystem hosting the application is case-sensitive (e.g., Linux/Unix).
  • Manually configure all Shiro filter chains to handle all possible case variations of protected filenames (not recommended due to complexity).

Resources

References

Published by the National Vulnerability Database Feb 9, 2026
Published to the GitHub Advisory Database Feb 9, 2026
Reviewed Feb 11, 2026
Last updated Feb 11, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(28th percentile)

Weaknesses

Authentication Bypass by Alternate Name

The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor. Learn more on MITRE.

CVE ID

CVE-2026-23903

GHSA ID

GHSA-c244-p6m5-vqj6

Source code

Credits

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