CVE-2021-3578

Name: CVE-2021-3578
Creator: NVD / NIST
Published: 2022-02-16T19:15:08.507+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 1.01%

Last modified Jun 17, 2026

CVE-2021-3578 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 1.01% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.01%

58.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Isync Project	Isync	< 1.3.6
Isync Project	Isync	1.4.0
Isync Project	Isync	1.4.1
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34
Debian	Debian Linux	9.0

References

http://www.openwall.com/lists/oss-security/2021/06/07/1Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1961710Not Applicable
https://bugzilla.redhat.com/show_bug.cgi?id=1967397Issue Tracking, Patch, Third Party Advisory
https://github.blog/2021-06-10-privilege-escalation-polkit-root-on-linux-with-bug/Not Applicable
https://lists.debian.org/debian-lts-announce/2022/07/msg00001.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RPIDLIJKNRJHUVBCL7QGAPAAVPIHQGXK/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U75UFEWRAZYKVL5NHMPBUOLWN3WXTOEI/
https://security.gentoo.org/glsa/202208-15Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/06/07/1Mailing List, Patch, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/06/07/1Mailing List, Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1961710Not Applicable
https://bugzilla.redhat.com/show_bug.cgi?id=1967397Issue Tracking, Patch, Third Party Advisory
https://github.blog/2021-06-10-privilege-escalation-polkit-root-on-linux-with-bug/Not Applicable
https://lists.debian.org/debian-lts-announce/2022/07/msg00001.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RPIDLIJKNRJHUVBCL7QGAPAAVPIHQGXK/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U75UFEWRAZYKVL5NHMPBUOLWN3WXTOEI/
https://security.gentoo.org/glsa/202208-15Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/06/07/1Mailing List, Patch, Third Party Advisory

Timeline

Published: Feb 16, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3578?

How severe is CVE-2021-3578?

CVE-2021-3578 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 1.01% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3578?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3578?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST