CVE-2021-20247
CVSS v3
7.4
HIGH
EPSS Score
1.9 %
exploit probability, as of 2026-10-19
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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Affected and fixed versions
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
- CVE-2021-20247 Red Hat Product Security
isync/mbsync: mailbox names returned by IMAP LIST/LSUB not validated
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.
Technical details
- Published
- 2021-02-23
Frequently asked questions
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