CVE-2025-29813: Azure DevOps Auth Bypass Vulnerability

CVE-2025-29813 Overview

CVE-2025-29813 is a critical authentication bypass vulnerability in Microsoft Azure DevOps that allows an unauthorized attacker to elevate privileges over a network. The vulnerability stems from authentication bypass by assumed-immutable data, specifically related to spoofable identity claims. This weakness enables attackers to manipulate identity claims that the system incorrectly assumes cannot be modified, leading to unauthorized privilege escalation.

Critical Impact

Unauthorized attackers can exploit spoofable identity claims to bypass authentication mechanisms and gain elevated privileges in Azure DevOps environments, potentially compromising CI/CD pipelines, source code repositories, and deployment configurations.

Affected Products

• Microsoft Azure DevOps

Discovery Timeline

• May 8, 2025 - CVE-2025-29813 published to NVD
• June 5, 2025 - Last updated in NVD database

Technical Details for CVE-2025-29813

Vulnerability Analysis

This vulnerability is classified under CWE-302 (Authentication Bypass by Assumed-Immutable Data) and CWE-287 (Improper Authentication). The flaw exists in how Azure DevOps handles identity claims during the authentication process. The system treats certain identity claim data as immutable and trustworthy when it should not, creating an opportunity for attackers to inject or modify these claims to impersonate other users or gain unauthorized access to resources.

The network-based attack vector means exploitation can occur remotely without requiring prior authentication or user interaction. An attacker who successfully exploits this vulnerability could gain access with elevated privileges, potentially allowing them to read sensitive source code, modify build pipelines, access secrets stored in Azure DevOps, or manipulate deployment workflows.

Root Cause

The root cause lies in the authentication mechanism's improper assumption that identity claim data cannot be spoofed or modified by external parties. When processing authentication requests, Azure DevOps fails to adequately validate the integrity and authenticity of identity claims, treating client-supplied data as trustworthy. This design flaw allows attackers to craft malicious requests with forged identity claims that the system accepts as legitimate.

Attack Vector

The vulnerability is exploitable over the network by unauthenticated attackers. The attack involves manipulating identity claims during the authentication flow to Azure DevOps. An attacker can craft specially formed authentication requests that include spoofed identity claims, which the vulnerable system accepts without proper validation.

The exploitation path typically involves:

1. Intercepting or crafting authentication requests to the Azure DevOps service
2. Modifying identity claim data to include elevated privilege attributes
3. Submitting the crafted request to bypass normal authentication checks
4. Gaining unauthorized access with elevated privileges

Due to the sensitive nature of this vulnerability and the lack of verified proof-of-concept code, detailed exploitation techniques are not provided. Refer to the Microsoft Security Update Guide for technical details.

Detection Methods for CVE-2025-29813

Indicators of Compromise

• Unusual authentication patterns or unexpected privilege escalation events in Azure DevOps audit logs
• Authentication requests with malformed or inconsistent identity claims
• Access to restricted repositories or pipelines by users without proper permissions
• Unexpected modifications to build pipelines, release definitions, or service connections

Detection Strategies

• Monitor Azure DevOps audit logs for authentication anomalies and privilege escalation events
• Implement alerts for unusual access patterns to sensitive repositories or project settings
• Review authentication logs for requests with inconsistent user identity attributes
• Enable and monitor Azure Active Directory sign-in logs for suspicious authentication attempts

Monitoring Recommendations

• Configure Azure Monitor alerts for critical Azure DevOps security events
• Implement continuous monitoring of service principal and user authentication activities
• Deploy SIEM integration to correlate Azure DevOps events with broader security telemetry
• Regularly audit user permissions and access control configurations in Azure DevOps

How to Mitigate CVE-2025-29813

Immediate Actions Required

• Review the Microsoft Security Update Guide for the latest remediation guidance
• Audit Azure DevOps organization settings and access permissions for unauthorized changes
• Review recent authentication logs for signs of exploitation
• Implement network-level restrictions to limit access to Azure DevOps services where possible

Patch Information

Microsoft has addressed this vulnerability in Azure DevOps. As this is a cloud service, Microsoft applies patches directly to the Azure DevOps infrastructure. Organizations using Azure DevOps Server (on-premises) should consult the Microsoft Security Update Guide for specific patch information and version requirements.

Workarounds

• Implement strict conditional access policies in Azure Active Directory for Azure DevOps access
• Enable multi-factor authentication for all Azure DevOps users
• Review and restrict service connections and service principal permissions to minimum required access
• Monitor for and investigate any suspicious authentication or authorization activities

Since this vulnerability affects a cloud service managed by Microsoft, the primary mitigation involves ensuring your Azure DevOps organization is using the latest service version and following Microsoft's security recommendations. For on-premises Azure DevOps Server deployments, apply the appropriate security updates as directed by Microsoft.