CVE-2021-20247

mediumpriority · track · 31EPSS 0.019 · 79 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.88% (79th) EPSS

CVSS 5.8 · medium

Is it mine?

8 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.4

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.8–7.4

v2.05.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 4.9

v3.17.4highCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 5.2

v3.16.8mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-22USprimaryCWE-20US

affected products (8)

Products and version ranges known to be affected.

n/a isync/mbsync≤ before 1.4.1enisa_euvdEU
n/a isync/mbsync≤ before 1.35enisa_euvdEU
debian debian linux= 9.0nvdUScpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*
fedoraproject extra packages for enterprise linux= 8.0nvdUScpe:2.3:a:fedoraproject:extra_packages_for_enterprise_linux:*:*:*:*:*:*:*:*
fedoraproject fedora= 32nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*
fedoraproject fedora= 33nvdUScpe:2.3:o:fedoraproject:fedora:*:*:*:*:*:*:*:*
mbsync project mbsync< 1.3.5nvdUScpe:2.3:a:mbsync_project:mbsync:*:*:*:*:*:*:*:*
mbsync project mbsync1.4.0 → 1.4.1nvdUScpe:2.3:a:mbsync_project:mbsync:*:*:*:*:*:*:*:*

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2021-02-23modified 2026-06-17

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+12523 more

references (22)

External citations — patches, advisories, analysis.

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