CVE-2021-20247

high
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
8.0

Description

A flaw was found in mbsync before v1.3.5 and v1.4.1. Validations of the mailbox names returned by IMAP LIST/LSUB do not occur allowing a malicious or compromised server to use specially crafted mailbox names containing '..' path components to access data outside the designated mailbox on the opposite end of the synchronization channel. The highest threat from this vulnerability is to data confidentiality and integrity.

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-2021-20247

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-202102-38

OS impact

OSVersionStatusFixed in
arch archfixed1.3.5-1
debian debianbookwormfixed1.3.0-2.1
debian debianbullseyefixed1.3.0-2.1
debian debianforkyfixed1.3.0-2.1
debian debiansidfixed1.3.0-2.1
debian debiantrixiefixed1.3.0-2.1

References

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