CVE-2021-3657

medium
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
5.5

Description

A flaw was found in mbsync versions prior to 1.4.4. Due to inadequate handling of extremely large (>=2GiB) IMAP literals, malicious or compromised IMAP servers, and hypothetically even external email senders, could cause several different buffer overflows, which could conceivably be exploited for remote code execution.

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-3657

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202112-5

OS impact

OSVersionStatusFixed in
arch archfixed1.4.4-1
debian debianbookwormfixed1.4.4-1
debian debianbullseyefixed1.3.0-2.2+deb11u1
debian debianforkyfixed1.4.4-1
debian debiansidfixed1.4.4-1
debian debiantrixiefixed1.4.4-1

References

Verify integrity in audit chain (admin only). AS-IS.