Red Hat: CVE-2026-117691

A flaw was found in the SAML HTTP-Redirect binding implementation of Keycloak. The issue occurs because the server processes percent-encoded parameter names (like %53AMLResponse) while the signature verification logic only checks literal parameter names. An attacker can use this discrepancy to provide a crafted, unsigned SAML message that the server processes instead of a legitimately signed one, leading to full account takeover of federated users.

The Red Hat Product Security team has assessed the severity of this vulnerability as Important, given that it allows for full account takeover of federated users. Successful exploitation allows an attacker to log in as any user and access their roles and data without authorization. The vulnerability's root cause is an inconsistent parsing of percent-encoded query parameters between the signature verification and message processing logic in the SAML redirect binding.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Bugzilla 2561977 : keycloak-services: keycloak-services: SAML redirect binding signature bypass via percent-encoded parameter names

CWE-347 : Improper Verification of Cryptographic Signature

Common Vulnerability Scoring System (CVSS) Score Details

Info alert: Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications ).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown

Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Understanding the Weakness (CWE)

Access Control,Integrity,Confidentiality

Technical Impact: Gain Privileges or Assume Identity; Modify Application Data; Execute Unauthorized Code or Commands

An attacker could gain access to sensitive data and possibly execute unauthorized code.

Red Hat would like to thank Mayssen Aidoudi (Think-it GmbH) for reporting this issue.

Frequently Asked Questions

"Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.

The term 'Affected' means that our Analysis team has determined that this product, such as Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to address this issue in the near future. This includes all minor releases of this product unless noted otherwise in the Statement text.

Upgrade to a supported product version that includes a fix for this vulnerability (recommended).

Apply a mitigation (if one exists).

Customers with the Technical Account Manager (TAM) RHEL Security Select Add-on can review this CVE directly with their TAM.

Apply a mitigation (if one exists).

Red Hat Engineering focuses on addressing high-priority issues based on the impact and product lifecycle expectations. Therefore, lower-priority issues will not receive immediate fixes.

Customers with the technical account manager (TAM) RHEL Security Select Add-on can review this CVE directly with their TAM.

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