CVE-2021-20247

moderate-risk
Published 2021-02-23

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.

Do I need to act?

~
1.4% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.4/10 High
NETWORK / HIGH complexity
38
/ 100
moderate-risk
Severity 22/34 · High
Exploitability 4/34 · Minimal
Exposure 12/34 · Low