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Fencer Vulns
medium 4.2

CVE-2026-9689 json

Keycloak: org.keycloak.protocol.oidc: http parameter pollution in oidc redirect uri allows response parameter duplication - #ghi-604

published 2026-05-27 5 mo ago modified 2026-10-26 13 d ago also GHSA-wcvj-vpvw-9rr5 , EUVD-2026-32212

cvss
4.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

A flaw was found in Keycloak, an open-source identity and access management solution. When a client application is configured to accept broad redirect Uniform Resource Identifiers (URIs), a remote attacker can manipulate the authentication process by crafting a special web address. If a user clicks this link, the client application might incorrectly prioritize attacker-controlled information over legitimate data. This vulnerability, known as HTTP parameter pollution, could allow an attacker to bypass security measures or gain unauthorized access to resources.

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

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-2026-9689 updated cvss 4.2

keycloak: org.keycloak.protocol.oidc: HTTP Parameter Pollution in OIDC redirect URI allows response parameter duplication - #GHI-604

  • 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
5 mo ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
GitHub 3.1 4.2 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
>=26.5.0, <=26.6.4
<=26.4.7
 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-1288 Improper Validation of Consistency within Input

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.