CVE-2026-117691
Description
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.
Statement
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
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.
--- CME Mitigation Guidance (2026-11-06) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to align query parameter parsing between signature verification and request processing in Keycloak's SAML HTTP-Redirect binding so percent-encoded parameter names cannot evade signature checks: upgrade to the fixed Rhbk/Keycloak Rhel/Keycloak Services builds, which eliminates the parsing discrepancy between raw query parameter signature verification and decoded parameter processing in the SAML redirect binding, closing crafted HTTP GET request containing a percent-encoded unsigned SAML parameter placed before a legitimately signed parameter. Until patched, this is a concern on Keycloak instances configured to use SAML HTTP-Redirect binding for federated identity, so Audit and restrict account registration on external Identity Providers to prevent attackers from capturing legitimately signed redirect-binding messages. These controls limit blast radius and contain exploitation, but they do not fix the underlying SAML parameter parsing discrepancy signature bypass — apply the upstream patch to fully remediate.
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 | NVD | cve.org | |
|---|---|---|---|
| Base Score | 9.1 | N/A | 9.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
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.
Acknowledgements
Red Hat would like to thank Mayssen Aidoudi (Think-it GmbH) for reporting this issue.
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