CVE-2025-49676: Critical Heap-Based Buffer Overflow Vulnerability in Windows RRAS

Overview

The Common Vulnerabilities and Exposures (CVE) system has recently identified a critical security vulnerability, tagged CVE-2025-49676, which affects the Windows Routing and Remote Access Service (RRAS). This vulnerability is a heap-based buffer overflow that could allow an unauthorized attacker to execute malicious code over a network, potentially leading to system compromise or data leakage. Given the widespread use of Windows RRAS in both corporate and personal environments, this vulnerability presents a significant risk to a large number of systems worldwide.

Vulnerability Summary

CVE ID: CVE-2025-49676
Severity: Critical (8.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage

Affected Products

Product | Affected Versions

Windows RRAS | All versions prior to patch

How the Exploit Works

The vulnerability resides in a heap-based buffer overflow in Windows RRAS. In simple terms, the software fails to properly allocate or control the memory buffer during data transfer operations. This flaw allows an attacker to overflow the buffer with more data than it can contain, leading to corruption of adjacent memory spaces. The attacker can exploit this vulnerability to inject and execute arbitrary code, which could lead to full system compromise or potential data leakage.

Conceptual Example Code

Below is a
conceptual
example of how the vulnerability might be exploited. This example is a hypothetical malicious payload sent over a network to a vulnerable Windows RRAS system.

POST /RRAS/vulnerable_endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/octet-stream
{ "buffer_overflow_payload": "A".repeat(5000) } // Example of a buffer overflow attack

In the above example, we are sending a large amount of data (“A”.repeat(5000)) to the vulnerable endpoint. This data is larger than the buffer size and leads to overflow, thereby exploiting the vulnerability.

Mitigation Guidance

To mitigate this vulnerability, users are urged to apply the vendor-provided patch as soon as it is available. As a temporary solution, users can employ a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and block attempts to exploit this vulnerability. It’s also recommended that users regularly update their systems and employ robust security practices to protect against such vulnerabilities.