CVE-2026-9689
Keycloak: org.keycloak.protocol.oidc: http parameter pollution in oidc redirect uri allows response parameter duplication - #ghi-604
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
4.2
Keycloak: org.keycloak.protocol.oidc: http parameter pollution in oidc redirect uri allows response parameter duplication - #ghi-604
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.
- Record
CVE-2026-9689- CVSS 3.1
- 4.2 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N - Weakness
- CWE-1288
- Updated
- 2026-11-02
EUVDEUVD-2026-32212
4.2
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.
- Record
EUVD-2026-32212- CVSS 3.1
- 4.2 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-wcvj-vpvw-9rr5
4.2
Keycloak Services has Improper Validation of Consistency within Input
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.
- Record
GHSA-wcvj-vpvw-9rr5- CVSS 3.1
- 4.2 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N - Weakness
- CWE-1288
- Updated
- 2026-11-02
NVD
4.2
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.
- Record
CVE-2026-9689- CVSS 3.1
- 4.2 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N - Weakness
- CWE-1288
- Updated
- 2026-11-02
OSVGHSA-wcvj-vpvw-9rr5
4.2
Keycloak Services has Improper Validation of Consistency within Input
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.
- Record
GHSA-wcvj-vpvw-9rr5- CVSS 3.1
- 4.2 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N - Weakness
- CWE-1288
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.keycloak:keycloak-servicesMaven |
26.5.0 to 26.6.4 | None known |
org.keycloak:keycloak-servicesMaven |
through 26.4.7 | None known |
org.keycloak:keycloak-servicesMaven |
26.5.0 to 26.6.4, plus listed versions 26.5.126.5.226.5.326.5.426.5.5 Show 6 moreShow less26.5.626.5.726.6.026.6.126.6.226.6.3 |
None known |
org.keycloak:keycloak-servicesMaven |
through 26.4.7, plus listed versions 1.0-alpha-11.0-alpha-1-120620131.0-alpha-21.0-alpha-31.0-alpha-4 Show 45 moreShow less1.0-beta-11.0-beta-1-201505211.0-beta-1-201505231.0-beta-21.0-beta-31.0-beta-41.0-final1.0-rc-11.0-rc-21.0.1.Final1.0.2.Final1.0.3.Final1.0.4.Final1.0.5.Final1.1.0.Beta11.1.0.Beta21.1.0.Final1.1.1.Final1.2.0.Beta11.2.0.CR11.2.0.Final1.3.0.Final1.3.1.Final1.4.0.Final1.5.0-Final1.5.0.Final1.5.1.Final1.6.0.Final1.6.1.Final1.7.0.CR11.7.0.Final1.8.0.Alpha11.8.0.CR11.8.0.CR21.8.0.CR31.8.0.Final1.8.1.Final1.9.0.CR11.9.0.Final1.9.1.Final1.9.2.Final1.9.3.Final1.9.4.Final1.9.5.Final1.9.7.Final |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-9689 is a medium vulnerability (CVSS 4.2) in Red Hat Build Of Keycloak 26.4, published May 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 25th percentile. No source names a fixed version.
References
access.redhat.com/errata/RHSA-2026:50846
access.redhat.com/errata/RHSA-2026:50847
access.redhat.com/errata/RHSA-2026:50848
access.redhat.com/errata/RHSA-2026:50849
access.redhat.com/security/cve/CVE-2026-9689
bugzilla.redhat.com/show_bug.cgi?id=2481845
Show 8 moreShow less
nvd.nist.gov/vuln/detail/CVE-2026-9689
github.com/keycloak/keycloak/issues/49430
github.com/keycloak/keycloak/pull/49959
github.com/keycloak/keycloak/commit/18832bcae5bebd5a1d66c2ec5fcd640e576fa625
github.com/keycloak/keycloak/commit/1f58a4b79a258bcf2ef86b58fbf0016cdb91291f
github.com/keycloak/keycloak/commit/267a1a33d4dc1eac7622614ba9772b4e1e35726f
github.com/advisories/GHSA-wcvj-vpvw-9rr5
github.com/keycloak/keycloak
Left out here: 165 versions. The JSON record has them.