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Vulnerability · Published Feb 18, 2022 · Assigned by fedora

CVE-2021-3657

Critical 9.8

In plain English

A critical-severity memory corruption in isync. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 3.5% (higher than 89% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)9.8Critical
Exploit odds (30 days)3.5%top 10.8% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

A flaw was found in mbsync versions prior to 1.4.4. Due to inadequate handling of extremely large (>=2GiB) IMAP literals, malicious or compromised IMAP servers, and hypothetically even external email senders, could cause several different buffer overflows, which could conceivably be exploited for remote code execution.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20isync1.4.4-r0ALPINE-CVE-2021-3657
Alpine:v3.21isync1.4.4-r0ALPINE-CVE-2021-3657
Alpine:v3.22isync1.4.4-r0ALPINE-CVE-2021-3657
Alpine:v3.23isync1.4.4-r0ALPINE-CVE-2021-3657
Alpine:v3.24isync1.4.4-r0ALPINE-CVE-2021-3657
Debian:12isync1.4.4-1DEBIAN-CVE-2021-3657
Debian:13isync1.4.4-1DEBIAN-CVE-2021-3657
Debian:14isync1.4.4-1DEBIAN-CVE-2021-3657
Ubuntu:22.04:LTSisyncno fix listedUBUNTU-CVE-2021-3657
Ubuntu:24.04:LTSisyncno fix listedUBUNTU-CVE-2021-3657
Ubuntu:25.10isyncno fix listedUBUNTU-CVE-2021-3657
Ubuntu:26.04:LTSisyncno fix listedUBUNTU-CVE-2021-3657
Ubuntu:26.10isyncno fix listedUBUNTU-CVE-2021-3657

Affected products (as reported)

VendorProductVersions
n/a isync isync 1.4.4

Weakness: CWE-119

References