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Vulnerability record · CVE-2009-3677 · published 9 December 2009

CVE-2009-3677: Microsoft windows 2000 code injection vulnerability

Microsoft · Windows 2000

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."

10.0 CVSS 2.0 High EPSS 22% · top 2.4% CWE-94 · Code injectionCWE-255 · CWE-255
10.0CVSS 2.0 base score
22%EPSS exploitation probability, 30 days
NoNot in CISA KEV
5Affected product versions listed by NVD
8References
16 Jun 2026Last modified by NVD

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."

AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

5 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://www.securitytracker.com/id?1023291
http://www.us-cert.gov/cas/techalerts/TA09-342A.html US Government Resource
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 US Government Resource
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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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2009-3677), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.