PT-2026-30582 · Red Hat · Keycloak

Osidb Bzimport · Published 2026-04-06 · Updated 2026-04-06 · CVE-2026-37977

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Name of the Vulnerable Software and Affected Versions Keycloak (affected versions not specified)

Description A flaw exists in Keycloak that allows a remote attacker to exploit a Cross-Origin Resource Sharing (CORS) header injection in the User-Managed Access (UMA) token endpoint. The issue arises because the azp claim from a client-supplied JSON Web Token (JWT) is used to set the Access-Control-Allow-Origin header before JWT signature validation. A crafted JWT with a controlled azp value can be reflected as the CORS origin, potentially exposing low-sensitivity information from authorization server error responses, but only when a client is misconfigured with webOrigins: ['*'].

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Origin Validation Error

Weakness Enumeration

CWE-346

Related Identifiers

CVE-2026-37977

GHSA-5V8V-XVJV-57X7

Affected Products

Keycloak

References · 7

• https://bugzilla.redhat.com/show_bug.cgi?id=2455324 · Vendor Advisory
• https://access.redhat.com/security/cve/CVE-2026-37977 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-5v8v-xvjv-57x7 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-37977 · Security Note
• https://github.com/keycloak/keycloak · Note
• https://twitter.com/CVEnew/status/2041076949053837642 · Twitter Post
• https://twitter.com/infoflowcloud/status/2041077534012379377 · Twitter Post