CVE-2025-49737: Microsoft Teams Privilege Escalation Flaw

CVE-2025-49737 Overview

CVE-2025-49737 is a race condition vulnerability in Microsoft Teams that enables an authorized attacker to elevate privileges locally. The flaw stems from concurrent execution using a shared resource with improper synchronization (CWE-362), allowing low-privileged users to exploit timing windows to gain elevated system access.

Critical Impact

Local privilege escalation through race condition exploitation could allow attackers to gain elevated system privileges, potentially compromising the entire host system and accessing sensitive organizational data.

Affected Products

• Microsoft Teams (specific versions not disclosed)

Discovery Timeline

• 2025-07-08 - CVE-2025-49737 published to NVD
• 2025-07-10 - Last updated in NVD database

Technical Details for CVE-2025-49737

Vulnerability Analysis

This vulnerability exists due to improper synchronization when Microsoft Teams performs concurrent operations on shared resources. Race conditions occur when the outcome of an operation depends on the sequence or timing of uncontrollable events, creating a window where an attacker can manipulate the state of shared data or resources between the time they are checked and the time they are used.

The local attack vector requires the attacker to have prior access to the target system with low-privilege user credentials. While the attack complexity is high due to the precise timing required to exploit the race condition window, successful exploitation results in complete compromise of confidentiality, integrity, and availability at the local scope.

Root Cause

The vulnerability is rooted in CWE-362 (Concurrent Execution Using Shared Resource with Improper Synchronization). Microsoft Teams fails to properly implement synchronization mechanisms such as mutexes, semaphores, or critical sections when multiple threads or processes access shared resources. This creates a Time-of-Check Time-of-Use (TOCTOU) scenario where the state of a resource can change between validation and use.

Attack Vector

The attack is executed locally, requiring the attacker to first gain access to the target system through valid credentials or other means. The attacker must then:

1. Identify the shared resource and the timing window during which the race condition can be triggered
2. Execute carefully timed operations to manipulate the shared resource state
3. Win the race condition to achieve privilege escalation

The vulnerability mechanism involves exploiting the timing gap between when Microsoft Teams checks a resource's state and when it performs operations based on that check. For detailed technical information, refer to the Microsoft CVE-2025-49737 Advisory.

Detection Methods for CVE-2025-49737

Indicators of Compromise

• Unusual process spawning patterns from Microsoft Teams with elevated privileges
• Unexpected privilege changes for Teams-related processes
• Anomalous file system or registry access patterns during Teams execution
• Multiple rapid sequential operations targeting the same shared resources

Detection Strategies

• Monitor for privilege escalation events originating from Teams.exe or related processes
• Implement behavioral analysis to detect timing-based attack patterns against Teams processes
• Deploy endpoint detection rules for TOCTOU exploitation attempts
• Track process creation chains for unexpected parent-child relationships involving Teams

Monitoring Recommendations

• Enable detailed process auditing for Microsoft Teams application directories
• Configure security event logging for privilege changes and sensitive operation access
• Implement real-time monitoring of file system operations during Teams execution
• Deploy SentinelOne Singularity Platform for automated behavioral threat detection

How to Mitigate CVE-2025-49737

Immediate Actions Required

• Review the Microsoft CVE-2025-49737 Advisory for official patch guidance
• Apply Microsoft security updates as soon as they become available
• Restrict local access to systems running Microsoft Teams to trusted users only
• Enable SentinelOne endpoint protection to detect exploitation attempts

Patch Information

Microsoft has released security guidance for this vulnerability. Organizations should consult the official Microsoft Security Response Center advisory for specific patch versions and deployment instructions. Ensure automatic updates are enabled for Microsoft Teams to receive security patches promptly.

Workarounds

• Limit local user access to systems where Microsoft Teams is deployed
• Implement the principle of least privilege for all user accounts
• Consider temporary restrictions on Microsoft Teams usage on high-value systems until patching is complete
• Enable application whitelisting to prevent unauthorized code execution

# Verify Microsoft Teams version and update status
# Windows PowerShell
Get-AppxPackage -Name "*Teams*" | Select-Object Name, Version
# Check for available updates in Microsoft Store or Admin Center