{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-37977","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","state":"PUBLISHED","assignerShortName":"redhat","dateReserved":"2026-04-06T07:48:39.721Z","datePublished":"2026-04-06T08:38:36.657Z","dateUpdated":"2026-04-24T15:44:23.520Z"},"containers":{"cna":{"title":"Keycloak: org.keycloak.protocol.oidc.grants.ciba: keycloak: information disclosure via cors header injection due to unvalidated jwt azp claim","metrics":[{"other":{"content":{"value":"Low","namespace":"https://access.redhat.com/security/updates/classification/"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"},"format":"CVSS"}],"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: [\"*\"]`."}],"affected":[{"vendor":"Red Hat","product":"Red Hat Build of Keycloak","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","packageName":"rhbk/keycloak-rhel9","defaultStatus":"affected","cpes":["cpe:/a:redhat:build_keycloak:"]}],"references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-37977","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2455324","name":"RHBZ#2455324","tags":["issue-tracking","x_refsource_REDHAT"]}],"datePublic":"2026-04-06T08:34:01.137Z","problemTypes":[{"descriptions":[{"cweId":"CWE-346","description":"Origin Validation Error","lang":"en","type":"CWE"}]}],"x_redhatCweChain":"CWE-346: Origin Validation Error","timeline":[{"lang":"en","time":"2026-04-06T07:49:33.467Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-04-06T08:34:01.137Z","value":"Made public."}],"providerMetadata":{"orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","shortName":"redhat","dateUpdated":"2026-04-24T15:44:23.520Z"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-06T11:55:21.318112Z","id":"CVE-2026-37977","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-04-06T11:57:17.383Z"}}]}}