CVE-2026-37977

{"id": "CVE-2026-37977", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "secalert@redhat.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 3.7, "attackVector": "NETWORK", "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 1.4, "exploitabilityScore": 2.2}]}, "published": "2026-04-06T09:16:17.850", "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-37977", "source": "secalert@redhat.com"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2455324", "source": "secalert@redhat.com"}], "vulnStatus": "Awaiting Analysis", "weaknesses": [{"type": "Primary", "source": "secalert@redhat.com", "description": [{"lang": "en", "value": "CWE-346"}]}], "descriptions": [{"lang": "en", "value": "A flaw was found in Keycloak. A remote attacker can exploit a Cross-Origin Resource Sharing (CORS) header injection vulnerability in Keycloak's User-Managed Access (UMA) token endpoint. This flaw occurs because the `azp` claim from a client-supplied JSON Web Token (JWT) is used to set the `Access-Control-Allow-Origin` header before the JWT signature is validated. When a specially crafted JWT with an attacker-controlled `azp` value is processed, this value is reflected as the CORS origin, even if the grant is later rejected. This can lead to the exposure of low-sensitivity information from authorization server error responses, weakening origin isolation, but only when a target client is misconfigured with `webOrigins: [\"*\"]`."}], "lastModified": "2026-04-07T13:20:35.010", "sourceIdentifier": "secalert@redhat.com"}