# CVE-2021-44143: isync: A flaw was found in mbsync in isync 1.4.0 through 1.4.3

CVE-2021-44143 is fixed in isync on 1 platform, first by DEBIAN-CVE-2021-44143, released November 22, 2021. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2021-44143
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0378
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 22, 2021

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | isync Debian 12.15 (bookworm) | 1.4.4-1 | [DEBIAN-CVE-2021-44143](https://patchblox.com/security/data/fix/linux/debian-cve-2021-44143.md) | Nov 22, 2021 |
| Linux | isync Debian 13.5 (trixie) | 1.4.4-1 | [DEBIAN-CVE-2021-44143](https://patchblox.com/security/data/fix/linux/debian-cve-2021-44143.md) | Nov 22, 2021 |
| Linux | isync Debian 14 | 1.4.4-1 | [DEBIAN-CVE-2021-44143](https://patchblox.com/security/data/fix/linux/debian-cve-2021-44143.md) | Nov 22, 2021 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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