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Vulnerabilities

Vulnerability · CVE-2026-18217

Keycloak-services: keycloak-services: saml http-redirect binding response preserves query string leading to parameter pollution

Published Jul 31, 2026 · catalog updated Nov 6, 2026 · Red Hat Red Hat build of Keycloak 26.4

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

Check if you run it

No confirmed exploitation is on record for CVE-2026-18217. EPSS is 0.52%. Act only if a listed version of Red Hat Red Hat build of Keycloak 26.4 is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Low3.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.52%
Remediation
Advisory link
Affected products
vendor Red Hat Red Hat build of Keycloak 26.4 · vendor Red Hat Red Hat build of Keycloak 26.4.17 · vendor Red Hat Red Hat build of Keycloak 26.6 · vendor Red Hat Red Hat build of Keycloak 26.6.8

A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legitimate response to the attacker's parameters. This can cause some service providers to process the attacker's data instead of the real login information, potentially leading to a user being logged into the wrong account.

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.

  • vendor Red Hat Red Hat build of Keycloak 26.4version unspecified
  • vendor Red Hat Red Hat build of Keycloak 26.4.17version unspecified
  • vendor Red Hat Red Hat build of Keycloak 26.6version unspecified
  • vendor Red Hat Red Hat build of Keycloak 26.6.8version unspecified

How to fix CVE-2026-18217

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-2026-18217. EPSS is 0.52%. Act only if a listed version of Red Hat Red Hat build of Keycloak 26.4 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 0.52%. 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.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Nov 6, 2026 · BSI CERT-Bund

    Detected

    CVE-2026-18217 is listed by Keycloak: Mehrere Schwachstellen.

  2. Nov 6, 2026 · CVE.org

    Updated

    A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, an attacker can craft a request that includes malicious parameters. When a user authenticates, Keycloak appends its legit

Sources

  • BSI CERT-BundGovernment advisoryCVE-2026-18217

    Keycloak: Mehrere Schwachstellen

    wid.cert-bund.de
  • CVE.orgVulnerability recordCVE-2026-18217

    A flaw was found in the SAML protocol implementation of Keycloak, an open-source identity and access management solution. The issue occurs when Keycloak handles SAML authentication requests using the HTTP-Redirect binding. If a client is configured with a wildcard redirect URL, a

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-18217

    30-day exploitation probability 0.52%

    first.org

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 7, 2026
  • CVE.orgNov 7, 2026
  • BSI CERT-BundNov 7, 2026