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CVE-2009-3677

38
FAUCET Score

CVE-2009-3677 is a critical authentication bypass vulnerability affecting the Internet Authentication Service (IAS) in various Microsoft Windows operating systems, including Windows 2000, XP, Server 2003, Vista, and Server 2008. This flaw allows remote, unauthenticated attackers to gain unauthorized access to network resources by sending a malformed MS-CHAP v2 PEAP authentication request, bypassing credential verification. With a CVSS score of 10.0, the vulnerability presents a severe risk, enabling complete compromise of confidentiality, integrity, and availability. Despite its high severity and EPSS score, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_2000:*:sp4:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2003:*:sp2:*:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2008:*:*:itanium:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2008:*:*:x32:*:*:*:*:*
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_server_2008:*:*:x64:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

10.0HIGH

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

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
21.82%
Probability of exploitation in next 30 days
EPSS Percentile
97.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.2182 is in the 96th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

docs.microsoft.com / en-us/security-updates/securitybulletins/2009/ms09-071
oval.cisecurity.org / repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6209
securitytracker.com / id
us-cert.gov / cas/techalerts/TA09-342A.html
US Government Resource