Is CVE-2009-3766 being actively exploited?

CVE-2009-3766 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2009-3766?

CVE-2009-3766 has a CVSS 2.0 base score of 6.8 (MEDIUM).

CVE-2009-3766

MEDIUM · CVSS 6.8EPSS 1.1%EU EUVD

mutt_ssl.c in mutt 1.5.16 and other versions before 1.5.19, when OpenSSL is used, does not verify the domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.

Key facts

CVSS score: 6.8 (v2.0)
Severity: MEDIUM
CVSS vector: AV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness (CWE): CWE-310
EPSS score: 1.1% (67th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2009-3738)
Published: October 23, 2009
NVD last modified: June 16, 2026
Status: Modified

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2009-3738 in the EU Vulnerability Database. Last updated in EUVD on August 7, 2024.

View on the EU Vulnerability Database

Affected products

mutt / mutt
openssl / openssl

References

http://dev.mutt.org/trac/ticket/3087(Patch, Vendor Advisory)
http://marc.info/?l=oss-security&m=125198917018936&w=2(Mailing List, Third Party Advisory)
http://www.openwall.com/lists/oss-security/2009/10/26/1(Mailing List, Third Party Advisory)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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