{"cve":"CVE-2026-9704","nvd":{"published":"2026-05-27T14:17:40.480","modified":"2026-06-26T08:16:26.650","status":"Modified","description":"A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-1284"],"references":["https://access.redhat.com/errata/RHSA-2026:25097","https://access.redhat.com/errata/RHSA-2026:25098","https://access.redhat.com/errata/RHSA-2026:30049","https://access.redhat.com/errata/RHSA-2026:30050","https://access.redhat.com/security/cve/CVE-2026-9704"],"products":["redhat:build_of_keycloak"],"source":"nvd","synced_at":"2026-10-19T22:36:28.938604137+00:00"},"epss":{"cve":"CVE-2026-9704","score":0.0032,"percentile":0.25059,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-rr5q-3xwr-f323","url":"https://osv.dev/vulnerability/GHSA-rr5q-3xwr-f323","summary":"Keycloak Vulnerable to Improper Validation of Specified Quantity in Input","modified":"2026-07-01T19:26:31.260306Z","packages":[{"ecosystem":"Maven","name":"org.keycloak:keycloak-server-spi-private","purl":"pkg:maven/org.keycloak/keycloak-server-spi-private","ranges":["<26.6.3"],"fixed":["26.6.3"]},{"ecosystem":"Maven","name":"org.keycloak:keycloak-services","purl":"pkg:maven/org.keycloak/keycloak-services","ranges":["<26.6.3"],"fixed":["26.6.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}