Vulnerability · Published Oct 28, 2026 · Assigned by WSO2
CVE-2026-6647Incomplete OAuth Token Revocation via Case Mismatch in WSO2 Identity Server Allows Continued Access After Lifecycle Events
High 7.4
In plain English
A high-severity security flaw in WSO2 Carbon OAuth from WSO2. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| WSO2 | WSO2 Identity Server | 7.2.0 – before 7.2.0.21 |
| WSO2 | WSO2 Carbon OAuth | 7.0.385 – before 7.0.385.17 |
Weakness: CWE-613 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L