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CVE-2021-20247

HIGH
7.4
CVSS Score
Published: February 23, 2021 at 06:45 PM UTC
Updated: June 17, 2026 at 03:33 AM UTC
5 products affected across 4 vendorsDebian LinuxFedoraExtra Packages for Enterprise Linux

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Severity
HIGH7.4
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux· Debiandrupal
95%
9.0
Extra Packages for Enterprise Linux· Fedora Projectrpm
95%
8.0
Fedora· Fedora Projectrpm
95%
3233
Mbsync· Mbsync Project
95%
v < 1.3.51.4.0 ≤ v < 1.4.1
Affected range stops below 1.3.5, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.4.1, so it looks safe — our inference, not a vendor statement
Isync· Isync Project
60%
v < 1.35v < 1.4.1
Affected range stops below 1.35, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.4.1, so it looks safe — our inference, not a vendor statement

References (6)

x_refsource_MISCIssue TrackingThird Party Advisory
Source: [email protected]
https://bugzilla.redhat.com/show_bug.cgi?id=1928963
Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2022/07/msg00001.html
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CAXQLCK35QGRCRENRTGKJO4VVZGUXUJJ/
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GVDEBZQJMWDW5JFK4NTHH6DAFNAZTESW/
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202208-15
x_refsource_MISCExploitMailing ListThird Party Advisory
Source: [email protected]
https://www.openwall.com/lists/oss-security/2021/02/22/1

CVSS

7.4HIGH[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20CWE-22

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