{"schemaVersion":3,"id":"CVE-2026-16093","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.","dates":{"published":"2026-07-17T16:42:52.407Z","modified":"2026-09-16T18:34:08.940Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.4,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.4,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.4,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00393,"percentile":0.32008,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":0,"baselineDate":"2026-09-19T00:00:00.000Z","baselineScore":0.00393},"history":[{"date":"2026-09-14T00:00:00.000Z","score":0.00304,"percentile":null},{"date":"2026-09-15T00:00:00.000Z","score":0.00304,"percentile":null},{"date":"2026-09-16T00:00:00.000Z","score":0.00304,"percentile":null},{"date":"2026-09-17T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-18T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-19T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00393,"percentile":0.32008}],"last30":[{"date":"2026-09-19T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-20T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-21T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-22T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-23T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-24T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-25T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-26T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-27T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-28T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-29T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-09-30T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-01T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-02T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-03T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-04T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-05T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-06T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-07T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-08T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-09T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00393,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00393,"percentile":0.32008}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-807","name":"Reliance on Untrusted Inputs in a Security Decision","description":"The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/807.html"}],"affected":[{"vendor":"redhat","product":"build_of_keycloak","name":"build of keycloak","label":"build_of_keycloak","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"na","noFixRecorded":false,"fixedIn":null}],"versionsText":"na","eol":null,"hubHref":"/vendor/redhat/build_of_keycloak"},{"vendor":"redhat","product":"data_grid","name":"data grid","label":"data_grid","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"8.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"8.0","eol":null,"hubHref":"/vendor/redhat/data_grid"},{"vendor":"redhat","product":"jboss_enterprise_application_platform_expansion_pack","name":"jboss enterprise application platform expansion pack","label":"jboss_enterprise_application_platform_expansion_pack","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"na","noFixRecorded":false,"fixedIn":null}],"versionsText":"na","eol":null,"hubHref":"/vendor/redhat/jboss_enterprise_application_platform_expansion_pack"},{"vendor":"redhat","product":"single_sign-on","name":"single sign-on","label":"single_sign-on","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"7.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"7.0","eol":null,"hubHref":"/vendor/redhat/single_sign-on"}],"affectedCount":4,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://access.redhat.com/errata/RHSA-2026:68277","label":"access.redhat.com/errata/RHSA-2026:68277","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:68278","label":"access.redhat.com/errata/RHSA-2026:68278","hostname":"access.redhat.com","tags":["Vendor Advisory","X Refsource REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-16093","label":"access.redhat.com/security/cve/CVE-2026-16093","hostname":"access.redhat.com","tags":["VDB Entry","X Refsource REDHAT","Vendor Advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2501729","label":"bugzilla.redhat.com/show_bug.cgi?id=2501729","hostname":"bugzilla.redhat.com","tags":["Issue Tracking","X Refsource REDHAT","Vendor Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-07-17T16:42:52.407Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-09-16T18:34:08.940Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":22,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T13:55:34.394Z","stale":false,"partial":false}}