{"cve":"CVE-2009-3677","nvd":{"published":"2009-12-09T18:30:00.517","modified":"2026-06-16T23:12:09.093","status":"Modified","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.\"","cvss_v4":null,"cvss_v3":null,"cwes":["CWE-94","CWE-255"],"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"],"products":["microsoft:windows_2000","microsoft:windows_server_2003","microsoft:windows_server_2008","microsoft:windows_vista","microsoft:windows_xp"],"source":"nvd","synced_at":"2026-10-19T19:54:26.868835795+00:00"},"epss":{"cve":"CVE-2009-3677","score":0.2182,"percentile":0.97641,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}