CVE-2026-18967
Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Keycloak-services: keycloak-services: saml onetimeuse assertion replay in idp-initiated broker flow
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.
- Record
CVE-2026-18967- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-294
- Updated
- 2026-11-02
EUVDEUVD-2026-53716
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.
- Record
EUVD-2026-53716- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-fghp-hcwh-75j2
A flaw was found in the SAML broker component of Keycloak, an identity and access management...
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.
- Record
GHSA-fghp-hcwh-75j2- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-294
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-18967- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-294
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-18967 is a medium vulnerability (CVSS 6.4) in Red Hat Build Of Keycloak, published August 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.23%, the 14th percentile. No source names a fixed version.