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USN-4403-1: Mutt vulnerability and regression

24 June 2020

Mutt could be made to enable MITM attacks if it received a specially crafted request.



  • mutt - text-based mailreader supporting MIME, GPG, PGP and threading


It was discovered that Mutt incorrectly handled certain requests.
An attacker could possibly use this issue to enable MITM attacks.

This update also address a regression caused in the last update USN-4401-1.
It only affected Ubuntu 12.04 ESM, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS and Ubuntu 19.10.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 20.04
Ubuntu 19.10
Ubuntu 18.04
Ubuntu 16.04
Ubuntu 12.04

After a standard system update you need to restart mutt to make
all the necessary changes.