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Fencer Intel
medium 4.3

CVE-2026-9798 json

Keycloak: keycloak: brute-force protection bypass in ciba flow

published 5mo ago modified 16d ago also GHSA-q6h7-xxp7-7429 , EUVD-2026-32717

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 31%
public exploits
0
none known

Summary

A flaw was found in Keycloak, an open-source identity and access management solution. When a user account is temporarily locked due to repeated failed login attempts, an attacker with valid client credentials can exploit the Client-Initiated Backchannel Authentication (CIBA) flow to bypass this brute-force protection. This allows continued authentication attempts and token issuance even when the account should be locked, potentially enabling further unauthorized access attempts.

Patch / fix

  • Red Hat Red Hat build of Keycloak 26.4 26.4-22, 26.4.14-1
  • Red Hat Red Hat build of Keycloak 26.6 26.6-11, 26.6.5-1

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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-2026-9798 updated cvss 4.3

keycloak: Keycloak: Brute-force protection bypass in CIBA flow

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-22, rhbk/keycloak-rhel9-operator 26.4-22, rhbk/keycloak-operator-bundle 26.4.14-1
    fixed: vendor fix RHSA-2026:50847
  • Red Hat build of Keycloak 26.4.14
    fixed: vendor fix RHSA-2026:50846
  • Red Hat build of Keycloak 26.6 rhbk/keycloak-rhel9 26.6-11, rhbk/keycloak-rhel9-operator 26.6-11, rhbk/keycloak-operator-bundle 26.6.5-1
    fixed: vendor fix RHSA-2026:50849
  • Red Hat build of Keycloak 26.6.5
    fixed: vendor fix RHSA-2026:50848

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
5mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

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

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<=26.4.7
>=26.5.0, <=26.6.4
 no fix listed

Affected products

  • Red Hat Red Hat build of Keycloak 26.4
  • Red Hat Red Hat build of Keycloak 26.4.14
  • Red Hat Red Hat build of Keycloak 26.6
  • Red Hat Red Hat build of Keycloak 26.6.5

Classification

Weakness
  • CWE-305 Authentication Bypass by Primary Weakness

References

Sources

Fencer Intel 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.