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Fencer Vulns
medium 4.3

CVE-2026-8830 json

Keycloak: org.keycloak/keycloak-services: keycloak: policy bypass during webauthn credential registration via client-side javascript manipulation

published 2026-05-19 5 mo ago modified 2026-07-23 3 mo ago also GHSA-g8vr-x4qh-25qg , EUVD-2026-30841

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

A flaw was found in Keycloak. An authenticated user can bypass configured WebAuthn policies during credential registration by manipulating client-side JavaScript. This occurs because the server-side processAction() fails to validate that the newly created credential's parameters, such as public key algorithms, match the realm's configured WebAuthn policies. This could lead to the creation of credentials that do not adhere to administrative security requirements, potentially weakening the overall security posture of the system by allowing non-compliant authentication methods.

Patch / fix

  • maven org.keycloak:keycloak-services 26.6.3
  • Red Hat Red Hat build of Keycloak 26.4 26.4-19, 26.4.13-1
  • Red Hat Red Hat build of Keycloak 26.6 26.6-6, 26.6.3-3

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-8830 updated cvss 4.3

keycloak: org.keycloak/keycloak-services: Keycloak: Policy bypass during WebAuthn credential registration via client-side JavaScript manipulation

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-19, rhbk/keycloak-rhel9-operator 26.4-19, rhbk/keycloak-operator-bundle 26.4.13-1
    fixed: vendor fix RHSA-2026:30050
  • Red Hat build of Keycloak 26.4.13
    fixed: vendor fix RHSA-2026:30049
  • Red Hat build of Keycloak 26.6 rhbk/keycloak-rhel9 26.6-6, rhbk/keycloak-rhel9-operator 26.6-6, rhbk/keycloak-operator-bundle 26.6.3-3
    fixed: vendor fix RHSA-2026:25097
  • Red Hat build of Keycloak 26.6.3
    fixed: vendor fix RHSA-2026:25098

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<26.6.3
26.6.3

Affected products

  • Red Hat Red Hat build of Keycloak 26.4
  • Red Hat Red Hat build of Keycloak 26.4.13
  • Red Hat Red Hat build of Keycloak 26.6
  • Red Hat Red Hat build of Keycloak 26.6.3

Classification

Weakness
  • CWE-603 Use of Client-Side Authentication

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.