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Vulnerability record · CVE-2026-18967 · published 6 August 2026

CVE-2026-18967: Redhat build of keycloak authentication bypass by capture-replay vulnerability

Redhat · Build Of Keycloak

A flaw was found in the SAML broker component of Keycloak, an identity and access management solution. When configured as a SAML broker using the IdP-Initiated flow, Keycloak fails to enforce the OneTimeUse condition in SAML assertions. This allows an attacker who captures a valid, unused assertion to replay it multiple times. Successful exploitation could allow an attacker to hijack a user's session and gain unauthorized access to the system as that user.

8.1 CVSS 3.1 High EPSS 0.23% · top 87.2% CWE-294 · Authentication bypass by capture-replay
8.1CVSS 3.1 base score
0.23%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
10 Aug 2026Last modified by NVD

Description

A flaw was found in the SAML broker component of Keycloak, an identity and access management solution. When configured as a SAML broker using the IdP-Initiated flow, Keycloak fails to enforce the OneTimeUse condition in SAML assertions. This allows an attacker who captures a valid, unused assertion to replay it multiple times. Successful exploitation could allow an attacker to hijack a user's session and gain unauthorized access to the system as that user.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://access.redhat.com/security/cve/CVE-2026-18967 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2511604 Permissions Required

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-18967), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.