Cyber Resilience

CVE-2026-18967

Auth Bypass in Redhat Build Of Keycloak

Auth Bypass
Published
06 August 2026
Modified
10 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 6.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
EPSS Score 0.0014 4th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2026-18967 is a medium-severity Authentication Bypass by Capture-replay (CWE-294) vulnerability in Redhat Build Of Keycloak. Its CVSS base score is 6.4 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Network Sniffing (T1040); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and SC-8 (Transmission Confidentiality and Integrity) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-294

Related Threats

MITRE ATT&CK Enterprise Techniques

T1040 Network Sniffing Credential Access
Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network.
attack.mitre.org →
T1550.003 Pass the Ticket Lateral Movement
Adversaries may “pass the ticket” using stolen Kerberos tickets to move laterally within an environment, bypassing normal system access controls.
attack.mitre.org →
T1550.004 Web Session Cookie Lateral Movement
Adversaries can use stolen session cookies to authenticate to web applications and services.
attack.mitre.org →
T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1021 Remote Services Lateral Movement
Adversaries may use [Valid Accounts](https://attack.
attack.mitre.org →
T1021.002 SMB/Windows Admin Shares Lateral Movement
Adversaries may use [Valid Accounts](https://attack.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-37982Same product: Redhat Build Of Keycloak
CVE-2026-14209Same product: Redhat Build Of Keycloak
CVE-2026-16104Same product: Redhat Build Of Keycloak
CVE-2026-18215Same product: Redhat Build Of Keycloak
CVE-2025-3910Same product: Redhat Build Of Keycloak
CVE-2026-37977Same product: Redhat Build Of Keycloak
CVE-2026-16442Same product: Redhat Build Of Keycloak
CVE-2026-7507Same product: Redhat Build Of Keycloak
CVE-2026-8922Same product: Redhat Build Of Keycloak
CVE-2026-16089Same product: Redhat Build Of Keycloak

Affected Assets

redhat
build of keycloak
all versions
redhat
jboss enterprise application platform expansion pack
all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V10.4.16
  • V10.5.1

Mitigating Controls (NIST 800-53 r5) AI

SC-23 Session Authenticity good match

Session authenticity mechanisms directly stop replay of captured authentication traffic by enforcing freshness or cryptographic binding.

SC-8 Transmission Confidentiality and Integrity good match

Transmission integrity (with anti-replay) stops captured messages from being accepted as valid later.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-04 mostly match
prevents

Protecting and verifying identity assertions prevents replay of captured authentication material.

PR.DS-02 mostly match
prevents

Encryption and integrity protections for data-in-transit directly block capture-replay of credentials or tokens.

DE.CM-01 partial match
prevents

Network monitoring may detect anomalous replays after the fact but does not prevent the design flaw.

PR.AA-03 partial match
prevents

Strong authentication methods can reduce replay risk but do not inherently address captured messages.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.24 Use of cryptography mostly match
prevents

Cryptographic protections (e.g., nonces, timestamps, message authentication codes) make captured authentication messages unusable for replay.

A.8.5 Secure authentication mostly match
prevents

Secure authentication mechanisms directly prevent replay attacks by requiring fresh, non-replayable credentials or tokens.

A.8.20 Networks security partial match
mitigates

Network security controls such as encryption and integrity protection reduce the feasibility of capturing and replaying authentication traffic.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate replay-resistant authentication designs, but the control itself does not prescribe the technical measures.

References