Overview
The vulnerability identified as CVE-2025-49669 is a severe security flaw found in Microsoft’s Windows Routing and Remote Access Service (RRAS). This critical vulnerability allows an unauthorized attacker to cause a heap-based buffer overflow, enabling the execution of arbitrary code over a network. It is a significant concern for organizations that leverage Windows RRAS, as it could potentially lead to complete system compromise or data leakage.
Vulnerability Summary
CVE ID: CVE-2025-49669
Severity: Critical, CVSS v3.0 Score: 8.8
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential for system compromise and data leakage
Affected Products
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Product | Affected Versions
Microsoft Windows RRAS | All current versions until patched
How the Exploit Works
The vulnerability lies in the improper handling of certain requests by the Windows RRAS. When an oversize packet is sent to the server, it can trigger a heap-based buffer overflow. This overflow condition allows an attacker to overwrite memory with arbitrary data, which can lead to the execution of malicious code.
This code execution occurs within the context of the RRAS, which operates with high system privileges. Consequently, an attacker can leverage this to gain complete control over an affected system, allowing for actions such as data theft, system manipulation, or the deployment of further malware.
Conceptual Example Code
The following pseudocode illustrates a conceptual exploitation of this vulnerability:
POST /RRAS/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/octet-stream
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA... [continuing for an unusually large size]In this example, an unusually large amount of data (represented by “A”) is sent to the RRAS endpoint, causing a buffer overflow. The buffer overflow could allow the attacker to inject and execute malicious code.
Mitigations
Microsoft has released a patch to address this vulnerability, and all users of the affected software are strongly encouraged to apply this patch immediately. If applying the patch is not immediately feasible, the use of a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation. However, these should not be seen as a long-term solution, as they may not fully protect against all possible exploitation techniques.