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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-18967
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-06 07:16:29 UTC
Updated2026-08-10 19:15:58 UTC
DescriptionA 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.

Risk And Classification

Primary CVSS: v3.1 8.1 HIGH from [email protected]

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

EPSS: 0.001440000 probability, percentile 0.041290000 (date 2026-08-11)

Problem Types: CWE-294 | CWE-294 Authentication Bypass by Capture-replay

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary8.1HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1[email protected]Secondary6.4MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
3.1CNACVSS6.4MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Redhat Build Of Keycloak - All All All
Application Redhat Jboss Enterprise Application Platform Expansion Pack - All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat Build Of Keycloak Not specified Not specified
CNA Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack Not specified Not specified
CNA Red Hat Red Hat Single Sign-On 7 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/security/cve/CVE-2026-18967 [email protected] access.redhat.com Vendor Advisory
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com Permissions Required
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Lidor Vasker for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-07-31T14:42:39.000ZReported to Red Hat.
CNA2026-07-31T14:42:39.000ZMade public.

Workarounds

CNA: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

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