CVE-2021-44143

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-22 · updated 2026-06-17
Weakness: CWE-787

Description

A flaw was found in mbsync in isync 1.4.0 through 1.4.3. Due to an unchecked condition, a malicious or compromised IMAP server could use a crafted mail message that lacks headers (i.e., one that starts with an empty line) to provoke a heap overflow, which could conceivably be exploited for remote code execution.

Affected products

Debian Linux: 9.0, 10.0, 11.0
Fedoraproject Fedora: 34, 35
Isync Project Isync: from 1.4.0 through 1.4.3

References

http://www.openwall.com/lists/oss-security/2021/12/03/2
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=999804
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CYZ2GNB4ZO2T27D2XNUWMCS3THZYSJQU/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LCBSY7OZ57XNC6ZYXF6WU5KBSWITZVDX/
https://security.gentoo.org/glsa/202208-15
https://sourceforge.net/p/isync/isync/commit_browser
https://sourceforge.net/p/isync/isync/ref/master/tags/
http://www.openwall.com/lists/oss-security/2021/12/03/2
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=999804
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CYZ2GNB4ZO2T27D2XNUWMCS3THZYSJQU/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LCBSY7OZ57XNC6ZYXF6WU5KBSWITZVDX/
https://security.gentoo.org/glsa/202208-15

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