What’s Vulnerable › Vulnerabilities

CVE-2009-3677

• Severity: critical (CVSS 10.0 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 21.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2009-12-09 · updated 2026-06-16
• Weakness: CWE-94

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."

Affected products

• Microsoft Windows 2000: all versions
• Microsoft Windows Server 2003: all versions
• Microsoft Windows Server 2008: all versions
• Microsoft Windows Vista: all versions
• Microsoft Windows XP Service Pack 3: all versions

References

• http://www.securitytracker.com/id?1023291
• http://www.us-cert.gov/cas/techalerts/TA09-342A.html
• https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-071
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6209
• http://www.securitytracker.com/id?1023291
• http://www.us-cert.gov/cas/techalerts/TA09-342A.html
• https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-071
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6209

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