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Vulnerabilities

Security incident · CVE-2026-9086

Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass

Published Aug 25, 2026 · catalog updated Oct 29, 2026 · Keycloak vulnerable to cross-site

Last checked Oct 31, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-9086. EPSS is 0.78%. Act only if a listed version of Keycloak vulnerable to cross-site is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Keycloak vulnerable to cross-site).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.78%
Remediation
Version ranges on file
Affected products
Bitnami keycloak · Maven org.keycloak:keycloak-services · maven org.keycloak · maven org.keycloak:keycloak-services

### Description A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive or scheme. This Cross-Site Scripting (XSS) vulnerability allows for arbitrary code execution in the Keycloak origin when a victim clicks the crafted link, such as in the logout flow or the Admin Console.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Bitnami keycloak26.4.0 → 26.4.13
  • Maven org.keycloak:keycloak-services0 → 26.6.4
  • maven org.keycloakversion unspecified
  • maven org.keycloak:keycloak-services< 26.6.4

How to fix CVE-2026-9086

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-9086. EPSS is 0.78%. Act only if a listed version of Keycloak vulnerable to cross-site is installed.

Which versions are affected?

Compare what you have installed with 26.4.0 → 26.4.13, 0 → 26.6.4, < 26.6.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.78%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Keycloak security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 29, 2026 · GitHub Advisory Database

    Detected

    ### Description A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive or scheme. This Cross-Site Scripting (XSS) vu

  2. Oct 29, 2026 · GitHub Advisory Database

    Fix available

    org.keycloak:keycloak-services fixed in 26.6.4

  3. Oct 29, 2026 · GitHub Advisory Database

    Fix available

    org.keycloak:keycloak-services fixed in 26.6.4

  4. Oct 29, 2026 · GitHub Advisory Database

    Fix available

    keycloak fixed in 26.4.13

  5. Oct 29, 2026 · GitHub Advisory Database

    Fix available

    keycloak fixed in 26.4.13

  6. Oct 29, 2026 · GitHub Advisory Database

    Updated

    ### Description A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive or scheme. This Cross-Site Scripting (XSS) vu

Sources

  • CVE.orgVulnerability recordCVE-2026-9086

    Official CVE identifier

    cve.org
  • GitHub Advisory DatabasePackage advisoryGHSA-v3f7-2p4r-mwfw

    Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-9086

    A flaw was found in Keycloak. A remote attacker with administrative privileges, specifically those with manage-client permission or access to client registration endpoints, could bypass client Uniform Resource Identifier (URI) validation. This is achieved by registering a malicious client with a specially crafted redirect URI using a case-insensitive javascript: or data: scheme. This Cross-Site Sc

    advisories.gitlab.com
  • OpenSSF OSV / OSV ScannerPackage advisoryBIT-keycloak-2026-9086

    Keycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass

    osv.dev
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-v3f7-2p4r-mwfw

    Keycloak vulnerable to cross-site scripting (xss) via case-insensitive uri validation bypass

    osv.dev

References

Freshness

Last verified in this catalog Oct 30, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • GitLab Advisory DatabaseOct 31, 2026
  • CVE.orgOct 30, 2026
  • GitHub Advisory DatabaseOct 30, 2026
  • OpenSSF OSV / OSV ScannerOct 30, 2026
  • OpenSSF OSV / OSV ScannerOct 30, 2026