Vulnerability · Published Aug 6, 2026 · Assigned by redhat

CVE-2026-18967Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow

Medium 6.4

In plain English

A medium-severity security flaw in Red Hat Build of Keycloak from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).

Severity (CVSS 3.1)6.4Medium

Exploit odds (30 days)0.2%top 85.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
Red Hat	Red Hat Build of Keycloak	see references
Red Hat	Red Hat Build of Keycloak	see references
Red Hat	Red Hat Build of Keycloak	see references
Red Hat	Red Hat JBoss Enterprise Application Platform Expansion Pack	see references
Red Hat	Red Hat Single Sign-On 7	see references

Weakness: CWE-294 · Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

References

https://access.redhat.com/security/cve/CVE-2026-18967 vdb-entry, x_refsource_REDHAT
RHBZ#2511604 issue-tracking, x_refsource_REDHAT