CVE-2020-37248 Security feature bypass in OfflineIMAP
Attackers can perform man-in-the-middle attacks to strip TLS encryption, exposing user credentials in cleartext during IMAP synchronization.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-37248?
CVE-2020-37248 is a medium-severity vulnerability in OfflineIMAP, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
OfflineIMAP before 8.0.3 trusts the server with their STARTTLS capability prior to authentication, which allows STRIPTLS/man-in-the-middle attacks, taking over the connection and extracting account credentials in cleartext.
Weakness: CWE-348
Which versions are affected by CVE-2020-37248?
How do I fix CVE-2020-37248?
Upgrade to a fixed version.
Is CVE-2020-37248 being exploited?
There is no known exploitation of CVE-2020-37248 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2020-37248, GHSA-899r-9fxv-q4xm, UBUNTU-CVE-2020-37248.