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CVE-2026-18967

MEDIUM 6.4

Published 2026-08-06 · Last modified 2026-08-06

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.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.1%chance of exploitation in 30 days · 4th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

6.4CVSS 3.1 · MEDIUM

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityNone

What an attacker needs

  • ⚠Access: Must sit on the same / adjacent network
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: A user must take an action (click / open a file)
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-18967/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-18967/poc.json

Affected

Vendors Red Hat Redhat

Products Red Hat Build Of Keycloak Red Hat Jboss Enterprise Application Platform Expansion Pack Red Hat Single Sign On 7 Build Of Keycloak Jboss Enterprise Application Platform Expansion Pack

Weakness (CWE)

  • CWE-294: Authentication Bypass by Capture-replay

CVSS vector

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

Known Affected Software Configurations

VendorProductVersion range
RedhatBuild Of Keycloak*
RedhatJboss Enterprise Application Platform Expansion Pack*

All CVSS metrics

  • MEDIUM 6.4 v3.1 · CNA Primary
    CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
  • MEDIUM 6.4 v3.1 · NVD Secondary
    CVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
  • HIGH 8.1 v3.1 · NVD Primary
    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS