CVE-2025-21176 Overview
CVE-2025-21176 is a remote code execution vulnerability affecting Microsoft's .NET, .NET Framework, and Visual Studio products. This vulnerability allows an attacker to execute arbitrary code on a target system when a user interacts with specially crafted content. The vulnerability stems from a buffer over-read condition (CWE-126) in the affected components, which can be exploited remotely over the network.
Critical Impact
Successful exploitation enables remote code execution with full compromise of system confidentiality, integrity, and availability. The vulnerability requires user interaction but no prior authentication.
Affected Products
- Microsoft .NET 8.0.0 and 9.0.0
- Microsoft .NET Framework 3.5, 4.6, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, and 4.8.1
- Microsoft Visual Studio 2017
- Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
- Windows 11 (versions 22H2, 23H2, 24H2)
- Windows Server 2008, 2012, 2016, 2019, 2022 (including 23H2)
Discovery Timeline
- January 14, 2025 - CVE-2025-21176 published to NVD
- May 6, 2025 - Last updated in NVD database
Technical Details for CVE-2025-21176
Vulnerability Analysis
This remote code execution vulnerability exists due to improper handling of buffer boundaries within the .NET runtime and .NET Framework components. The underlying issue is classified as CWE-126 (Buffer Over-read), indicating that the affected code reads data beyond the allocated buffer boundaries. When exploited, this condition can lead to memory corruption that allows an attacker to gain control over program execution flow.
The attack requires user interaction, meaning a victim must open a malicious file or access attacker-controlled content for exploitation to succeed. Once triggered, the vulnerability provides the attacker with the same privileges as the compromised user, potentially leading to complete system compromise if the user has administrative rights.
Root Cause
The vulnerability originates from a buffer over-read condition in the .NET and .NET Framework codebase. This type of flaw occurs when code reads past the end of an allocated memory buffer, potentially accessing sensitive data or corrupting adjacent memory structures. In this case, the memory corruption can be leveraged to achieve arbitrary code execution.
The cross-platform nature of .NET means this vulnerability affects systems running Windows, macOS, and Linux where vulnerable versions of .NET or .NET Framework are deployed.
Attack Vector
The attack is network-based and requires user interaction. An attacker can exploit this vulnerability by:
- Crafting a malicious file or content that triggers the buffer over-read condition
- Delivering this content to a target user via email, web download, or other distribution methods
- Convincing the user to open or interact with the malicious content
- Upon interaction, the vulnerability is triggered, allowing code execution in the context of the user's session
The vulnerability does not require authentication to exploit, making it accessible to remote attackers who can deliver malicious content to potential victims.
Detection Methods for CVE-2025-21176
Indicators of Compromise
- Unexpected crashes or exceptions in .NET or Visual Studio applications with memory-related error codes
- Unusual process behavior from dotnet.exe, devenv.exe, or .NET-hosted applications
- Creation of unexpected child processes from .NET applications
- Suspicious network connections initiated by .NET runtime processes
Detection Strategies
- Monitor application event logs for .NET runtime exceptions indicating memory access violations
- Deploy endpoint detection rules to identify exploitation attempts targeting .NET Framework components
- Implement file integrity monitoring on .NET Framework installation directories
- Enable enhanced logging for Visual Studio and .NET application execution
Monitoring Recommendations
- Configure SentinelOne agents to monitor for suspicious behavior in .NET runtime processes
- Set up alerts for unusual memory allocation patterns in applications using .NET Framework
- Monitor for attempts to load malicious assemblies or execute code from unexpected locations
- Track file access patterns for .NET configuration files and assembly loading behavior
How to Mitigate CVE-2025-21176
Immediate Actions Required
- Apply Microsoft security updates for all affected .NET, .NET Framework, and Visual Studio installations immediately
- Prioritize patching systems running publicly accessible .NET applications
- Educate users about the risks of opening files from untrusted sources
- Review and restrict execution of .NET applications from untrusted locations
Patch Information
Microsoft has released security updates to address this vulnerability. Organizations should apply the patches available through the Microsoft Security Update Guide. The updates address the buffer over-read condition by implementing proper boundary checking in the affected .NET components.
For .NET 8.0 and 9.0 deployments, update to the latest SDK and runtime versions. For .NET Framework installations, apply the cumulative updates appropriate for your Windows version. Visual Studio 2017 users should install the latest available update.
Workarounds
- Restrict access to potentially malicious content until patches can be applied
- Implement application whitelisting to prevent unauthorized .NET applications from executing
- Configure email filtering to block suspicious attachments that could exploit this vulnerability
- Consider isolating high-risk .NET applications in sandboxed environments until patching is complete
# Verify installed .NET versions and check for updates
dotnet --list-sdks
dotnet --list-runtimes
# Update .NET SDK to latest version
dotnet sdk check
# For Windows, check Windows Update for .NET Framework patches
# Settings > Windows Update > Check for updates
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
