CVE-2026-6647

Incomplete OAuth Token Revocation via Case Mismatch in WSO2 Identity Server Allows Continued Access After Lifecycle Events

Published Oct 28, 2026 CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed
Description
In deployments of WSO2 Identity Server configured with a case-insensitive user store and a case-sensitive database for identity data, mismatches in username case handling can occur. This inconsistency results in OAuth token revocation operations failing to correctly identify usernames containing mixed-case characters during certain lifecycle events, preventing tokens from being invalidated.

A malicious actor can exploit this vulnerability by possessing a valid access or refresh token associated with a mixed-case username. In affected configurations, these tokens may not be revoked when expected. The actor can then leverage these unrevoked tokens, before their expiry, to continue performing actions that should have been restricted, effectively bypassing intended access controls.

Remediation

Vendor Solution

Follow the instructions given on https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5387/#solution

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Wso2 identity Server
Vendors & Products Wso2 identity Server
Type Values Removed Values Added
Description In deployments of WSO2 Identity Server configured with a case-insensitive user store and a case-sensitive database for identity data, mismatches in username case handling can occur. This inconsistency results in OAuth token revocation operations failing to correctly identify usernames containing mixed-case characters during certain lifecycle events, preventing tokens from being invalidated. A malicious actor can exploit this vulnerability by possessing a valid access or refresh token associated with a mixed-case username. In affected configurations, these tokens may not be revoked when expected. The actor can then leverage these unrevoked tokens, before their expiry, to continue performing actions that should have been restricted, effectively bypassing intended access controls.
Title Incomplete OAuth Token Revocation via Case Mismatch in WSO2 Identity Server Allows Continued Access After Lifecycle Events
First Time appeared Wso2
Wso2 wso2 Carbon Oauth
Wso2 wso2 Identity Server
Weaknesses CWE-613
CPEs cpe:2.3:a:wso2:wso2_carbon_oauth:*:*:*:*:*:*:*:*
cpe:2.3:a:wso2:wso2_identity_server:*:*:*:*:*:*:*:*
Vendors & Products Wso2
Wso2 wso2 Carbon Oauth
Wso2 wso2 Identity Server
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
WSO2
Published
Updated
Oct 29, 2026, 2:02 AM
Reserved
Apr 20, 2026, 5:10 AM
Status
Awaiting Analysis
Published
Oct 28, 2026, 8:18 PM
Modified
Oct 29, 2026, 4:08 PM