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6.4

msmtp can accept forged SSL certificates

CVE-2009-3942 · published 16 years ago
Summary

The msmtp email tool (versions before 1.4.19) may mishandle a special null character in a certificate's domain name. This allows an attacker to pretend to be a trusted mail server and intercept or alter messages. Upgrade msmtp to version 1.4.19 or later, or apply the provided patch, to stop this risk.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
martin_lambers msmtp <= 1.4.18
0.2.5
0.2.6
0.3.0
0.3.1
0.4.0
0.4.1
0.4.2
0.5.0
0.5.1
0.5.2
0.5.3
32 more version ranges
cpe:2.3:a:martin_lambers:msmtp:*:*:*:*:*:*:*:*
Original advisory text
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.5...
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.
References
Fix within
Internet-facing 14 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically (estimated)
  • Gives an attacker partial control (estimated)
Severity
6.4 Medium
Exploitation
1% chance of attack within 30 days
Type
CWE-310Cryptographic Issues
Timeline
Published16 Nov 2009
Updated4 Nov 2026
First seen29 Sep 2026
Sources
CVE-2009-3942 · NVD
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