How severe is CVE-2009-3942?

CVE-2009-3942 has a CVSS 2.0 base score of 6.4, rated medium severity.

Is CVE-2009-3942 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-3942?

CVE-2009-3942 primarily affects Martin Lambers Msmtp. In total, 44 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-3942?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-3942 published?

CVE-2009-3942 was published on 2009-11-16 and last updated on 2026-06-16.

CVE-2009-3942

CVE-2009-3942 is a medium-severity vulnerability in Martin Lambers Msmtp with a CVSS 2.0 base score of 6.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-310.

Key facts

Severity: Medium (CVSS 2.0 base score 6.4)
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-310
Affected product: Martin Lambers Msmtp
Published: 2009-11-16
Last modified: 2026-06-16

Description

Martin Lambers msmtp before 1.4.19, when OpenSSL is used, does not properly handle a '\0' character in a domain name in the (1) subject's Common Name or (2) Subject Alternative Name field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.

Frequently asked questions

What is CVE-2009-3942?: Martin Lambers msmtp before 1.4.19, when OpenSSL is used, does not properly handle a '\0' character in a domain name in the (1) subject's Common Name or (2) Subject Alternative Name field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.
How severe is CVE-2009-3942?: CVE-2009-3942 has a CVSS 2.0 base score of 6.4, rated medium severity.
Is CVE-2009-3942 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-3942?: CVE-2009-3942 primarily affects Martin Lambers Msmtp. In total, 44 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-3942?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2009-3942 published?: CVE-2009-3942 was published on 2009-11-16 and last updated on 2026-06-16.

References

Affected products (44)

cpe:2.3:a:martin_lambers:msmtp:*:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.2.5:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.2.6:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.3.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.3.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.4.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.4.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.4.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.5.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.5.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.5.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.5.3:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.3:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.4:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.5:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.6.6:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.7.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.7.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:0.7.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.0.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.2.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.2.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.2.3:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.2.4:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.1:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.2:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.3:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.4:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.5:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.6:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.7:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.8:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.9:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.10:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.12:*:*:*:*:*:*:*
cpe:2.3:a:martin_lambers:msmtp:1.4.13:*:*:*:*:*:*:*

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