CVE-2026-9689

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

MEDIUM
4.2
CVSS Score
Published: May 27, 2026 at 10:35 AM UTC
Updated: October 26, 2026 at 11:10 AM UTC
1 product affected across 1 vendorBuild of Keycloak

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Severity
MEDIUM4.2
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions26.4
Vendor states this is fixed in 26.4-22 (unaffected)
Vendor states this is fixed in 26.4.14 (unaffected)
Vendor states this is fixed in 26.4.14-1 (unaffected)
Vendor states this is fixed in 26.6-11 (unaffected)
Vendor states this is fixed in 26.6.5 (unaffected)
Vendor states this is fixed in 26.6.5-1 (unaffected)

References (6)

VDB Entryx_refsource_REDHATVendor Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-9689
Issue Trackingx_refsource_REDHATVendor Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2481845
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:50846
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:50847
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:50848
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:50849

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.2MEDIUMredhat
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-1288

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