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Fencer Vulns
high 7.8

CVE-2021-3578 json

A flaw was found in mbsync before v1.3.6 and v1.4.2, where an unchecked pointer cast allows a malicious or compromised server to write an a…

published 2022-02-16 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26887

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 64%
public exploits
0
none known

Summary

A flaw was found in mbsync before v1.3.6 and v1.4.2, where an unchecked pointer cast allows a malicious or compromised server to write an arbitrary integer value past the end of a heap-allocated structure by issuing an unexpected APPENDUID response. This could be plausibly exploited for remote code execution on the client.

Patch / fix

  • isync_project isync 1.3.6
  • isync Debian 14, Debian 13, Debian 12 1.3.0-2.2

debian advisories DEBIAN-CVE-2021-3578

  • isync openSUSE Tumbleweed 1.4.3-1.2
  • isync Package Hub 15 SP2 1.3.6-bp152.4.6.1
  • isync openSUSE Leap 15.2 1.3.6-lp152.4.6.1

opensuse advisories openSUSE-SU-2024:10866-1openSUSE-SU-2021:1185-1openSUSE-SU-2021:1170-1

  • isync Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 1.4.2-r0

alpine advisories ALPINE-CVE-2021-3578

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • isync Arch Linux 1.4.2-1

arch linux advisories AVG-2042

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3578 updated cvss 7.5

isync: unchecked pointer cast may lead to remote code execution

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.04% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a isync

Classification

Weakness
  • CWE-704 Incorrect Type Conversion or Cast

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.