What’s Vulnerable › Vulnerabilities

CVE-2020-14954

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-06-21 · updated 2026-06-17
• Weakness: CWE-74

Description

Mutt before 1.14.4 and NeoMutt before 2020-06-19 have a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a man-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."

Affected products

• Canonical Ubuntu Linux: 12.04, 16.04, 18.04, 19.10, 20.04
• Debian Linux: 9.0, 10.0, 8.0
• Fedoraproject Fedora: 31, 32
• mutt: before 1.14.4 — fixed in 1.14.4
• Neomutt: before 20200619 — fixed in 20200619
• openSUSE Leap: 15.1, 15.2

How to fix

Upgrade to a fixed version: mutt 1.14.4; Neomutt 20200619. Check the vendor advisory for mitigations.

References

• http://lists.mutt.org/pipermail/mutt-announce/Week-of-Mon-20200615/000023.html
• http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00064.html
• http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00070.html
• http://www.mutt.org/
• https://github.com/neomutt/neomutt/commit/fb013ec666759cb8a9e294347c7b4c1f597639cc
• https://github.com/neomutt/neomutt/releases/tag/20200619
• https://gitlab.com/muttmua/mutt/-/commit/c547433cdf2e79191b15c6932c57f1472bfb5ff4
• https://gitlab.com/muttmua/mutt/-/issues/248
• https://lists.debian.org/debian-lts-announce/2020/06/msg00039.html
• https://lists.debian.org/debian-lts-announce/2020/06/msg00040.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EFMEILCBKMZRRZDMUGWLVN4PQQ4VTAZE/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3LXFVPTLK4PNHL6MPKJNJQJ25CH7GLQ/

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