CVE-2026-107623
Description
A flaw was found in the OIDC Dynamic Client Registration (DCR) component of Keycloak. A bug in the response serialization causes the backchannel logout offline token revocation setting to be omitted from responses. When a client performs a standard update, this missing information causes the setting to be silently disabled. As a result, offline tokens may remain valid even after a user session is terminated via backchannel logout.
Statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires the attacker to have client management privileges. Successful exploitation allows an attacker to silently disable security settings that ensure offline tokens are revoked during backchannel logout, leading to persistent access after session termination. The vulnerability's root cause is a serialization bug in the OIDC Dynamic Client Registration response handler.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.3 | N/A | 4.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Acknowledgements
Red Hat would like to thank Peter Su (psu512) for reporting this issue.
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