CVE-2020-28896
mutt: Incorrect handling of invalid initial IMAP responses could lead to an authentication attempt over unencrypted connection
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · November 20, 2020
Updated · November 22, 2025
Description
Mutt before 2.0.2 and NeoMutt before 2020-11-20 did not ensure that $ssl_force_tls was processed if an IMAP server's initial server response was invalid. The connection was not properly closed, and the code could continue attempting to authenticate. This could result in authentication credentials being exposed on an unencrypted connection, or to a machine-in-the-middle.
Statement
Red Hat Product Security has rated the severity of this flaw as Moderate because although the Confidentiality impact is high, the attack complexity is also high as a particular attacker would at least need to coordinate social engineering a victim to connect to a bad server, and also perform a man-in-the-middle attack or perform similar interception of the connection. Please see the following page for details on Red Hat severity ratings with special attention to Moderate: https://access.redhat.com/security/updates/classification .
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 5.3CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE-319 · Cleartext Transmission of Sensitive Information