CVE-2021-44143 Memory corruption in n/a

What is CVE-2021-44143?

CVE-2021-44143 is a critical memory corruption vulnerability in Debian Debian Linux, published on 22 Nov 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-787

Which versions are affected by CVE-2021-44143?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Isync Project Isync.

How do I fix CVE-2021-44143?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-44143 being exploited?

There is no known exploitation of CVE-2021-44143 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-44143, GHSA-2h85-c54w-28vc, UBUNTU-CVE-2021-44143.