CVE-2009-3677
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…
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 21.8%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.
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 2.0
- 10.0 HIGHAV:N/AC:L/Au:N/C:C/I:C/A:C
- EPSS
- 21.82% probability · 98th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-94, CWE-255
- Affected
- microsoft/windows 2000 · microsoft/windows server 2003 · microsoft/windows server 2008 · microsoft/windows vista · microsoft/windows xp
- Source
- secure@microsoft.com
EPSS 21.8% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.securitytracker.com/id?1023291
- http://www.us-cert.gov/cas/techalerts/TA09-342A.htmlUS 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.htmlUS 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.