Main Vulnerability Database Vulnerabilities #VU146986

Input validation error in Keycloak - CVE-2026-37977

Published: September 5, 2026

Vulnerability identifier: #VU146986

CSH Severity: Low

CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-37977

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to disclose sensitive information.

The vulnerability exists due to improper input validation in CORS header handling when processing JWT azp claims. A remote user can provide a JWT with a crafted azp claim to disclose sensitive information.

Affected software

Keycloak
Red Hat build of Keycloak

How to mitigate CVE-2026-37977

Install security update from vendor's website.

Keycloak - update to 26.6.3
Red Hat build of Keycloak - addressed in versions 26.4.13, 26.6.3

External References

https://github.com/advisories/GHSA-5v8v-xvjv-57x7
https://github.com/keycloak/keycloak/releases/tag/26.6.3

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