CVE-2021-4126

NameCVE-2021-4126
DescriptionWhen receiving an OpenPGP/MIME signed email message that contains an additional outer MIME message layer, for example a message footer added by a mailing list gateway, Thunderbird only considered the inner signed message for the signature validity. This gave the false impression that the additional contents were also covered by the digital signature. Starting with Thunderbird version 91.4.1, only the signature that belongs to the top level MIME part will be considered for the displayed status. This vulnerability affects Thunderbird < 91.4.1.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2874-1, DSA-5034-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
thunderbird (PTS)buster1:91.12.0-1~deb10u1fixed
buster (security)1:102.6.0-1~deb10u1fixed
bullseye1:91.13.0-1~deb11u1fixed
bullseye (security)1:102.6.0-1~deb11u1fixed
bookworm, sid1:102.7.1-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
thunderbirdsourcestretch1:91.4.1-1~deb9u1DLA-2874-1
thunderbirdsourcebuster1:91.4.1-1~deb10u1DSA-5034-1
thunderbirdsourcebullseye1:91.4.1-1~deb11u1DSA-5034-1
thunderbirdsource(unstable)1:91.4.1-1

Notes

https://www.mozilla.org/en-US/security/advisories/mfsa2021-55/#CVE-2021-4126

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