CVE-2021-20247

PoC —

CVSS 3.1

7.4 high

EPSS

2%p78

Published

Feb 23, 2021 (Feb 23, 2021)

Modified

Jun 17, 2026

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.

Vendors: mbsync project fedoraproject debian
Products: mbsync, extra packages for enterprise linux, debian linux, fedora
Weakness: CWE-20, CWE-22
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

NVD CVE.org GitHub PoCs EPSS (1.9%)

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