CVE-2026-49331 in OpenShift Container Platform
Summary
by MITRE • 08/05/2026
A flaw was found in openshift/oauth-proxy. On paths configured to bypass authentication (skip-auth-regex), the proxy forwards client-supplied identity headers (X-Forwarded-User, X-Forwarded-Email, X-Forwarded-Access-Token) to the upstream application without stripping them. An unauthenticated attacker can inject forged identity headers on whitelisted paths.
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Analysis
by VulDB Data Team • 08/05/2026
This vulnerability exists within the openshift/oauth-proxy component where authentication bypass configurations fail to properly sanitize client-supplied identity headers. The flaw occurs when specific paths are configured to skip authentication through the skip-auth-regex parameter, yet the proxy continues to forward user identity information from headers such as X-Forwarded-User, X-Forwarded-Email, and X-Forwarded-Access-Token directly to upstream applications without removing or validating these headers first. This represents a critical security weakness that allows unauthenticated attackers to manipulate authentication state by injecting forged identity information into requests targeting paths that should normally require authentication. The vulnerability stems from inadequate input validation and header sanitization practices within the proxy's request processing pipeline, creating an attack surface where malicious actors can impersonate legitimate users or escalate privileges.
The technical implementation of this flaw violates fundamental security principles of least privilege and proper access control enforcement. According to CWE-284, this represents an improper access control vulnerability where the system fails to properly restrict access to protected resources. The issue specifically aligns with CWE-352, which addresses cross-site request forgery vulnerabilities that can occur when user-supplied data is not properly validated or sanitized before being processed by backend systems. From an operational perspective, this vulnerability creates a path for privilege escalation attacks where attackers can bypass authentication mechanisms entirely and assume the identity of other users within the system. The attack vector is particularly dangerous because it requires no valid credentials or session tokens to exploit, making it accessible to any attacker who can send HTTP requests to the affected paths.
The impact of this vulnerability extends beyond simple authentication bypass to potentially enable complete system compromise when combined with other attack vectors. An attacker could use this flaw to gain access to sensitive data, modify user permissions, or perform administrative actions within applications protected by the oauth-proxy. This represents a significant concern for organizations relying on OpenShift's authentication infrastructure, as it undermines the core security model that protects their applications and services. The vulnerability also demonstrates weaknesses in the principle of defense-in-depth, where multiple layers of security should protect against individual failures. From an ATT&CK framework perspective, this vulnerability maps to T1078 (Valid Accounts) and T1566 (Phishing), as it allows attackers to leverage forged identity information to gain unauthorized access to protected resources without requiring legitimate credentials.
Organizations should immediately implement mitigations including strict header sanitization policies that strip or validate all forwarded identity headers before passing them to upstream applications. The recommended approach involves configuring the oauth-proxy to explicitly clear or rewrite these headers for paths configured with skip-auth-regex, ensuring that no user-supplied identity information can be passed through to backend services. Additionally, implementing comprehensive monitoring and logging of authentication bypass activities can help detect exploitation attempts. Security teams should also conduct thorough audits of all proxy configurations to identify similar vulnerabilities across their infrastructure, particularly focusing on any custom implementations or third-party components that may exhibit similar behaviors. Regular security testing including penetration testing and vulnerability scanning should be performed to verify that header sanitization mechanisms are properly implemented and functioning as intended.