CVE-2009-3677
CWE-94Published: December 9, 2009· Updated: Jun 16, 2026
Official Description
The Internet Authentication Service (IAS) in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold and SP1, and Server 2008 Gold does not properly verify the credentials in an MS-CHAP v2 Protected Extensible Authentication Protocol (PEAP) authentication request, which allows remote attackers to access network resources via a malformed request, aka "MS-CHAP Authentication Bypass Vulnerability."
Technical Analysis
CVE-2009-3677 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (8)
Quick Facts
Related CVEs (CWE-94)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2009-3677 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts