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CVE-2021-3578

A flaw was found in mbsync before v1.3.6 and v1.4.2, where an unchecked pointer cast allows a...

7.8 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.04%Down 2.9 points since Feb 17, 2022
90%50%10%1%

What each source reports

NVD Score used 7.8

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.

Record
CVE-2021-3578
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.2 HighAV:L/AC:L/Au:N/C:C/I:C/A:C
Weakness
CWE-704
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-3578
Weakness
CWE-704
Updated
2026-11-02
EUVDEUVD-2021-26887 No score

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.

Record
EUVD-2021-26887
Updated
2026-11-03
GitHub AdvisoriesGHSA-4r75-vj28-w5c7 7.8

A flaw was found in mbsync before v1.3.6 and v1.4.2, where an unchecked pointer cast allows a...

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.

Record
GHSA-4r75-vj28-w5c7
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-704
Updated
2026-11-02
OSVALPINE-CVE-2021-3578 7.8

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.

Record
ALPINE-CVE-2021-3578
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-03
OSV 7.8

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.

Record
CVE-2021-3578
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 5 moreShow less
OSVDEBIAN-CVE-2021-3578 7.8

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.

Record
DEBIAN-CVE-2021-3578
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-3578 7.8

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.

Record
UBUNTU-CVE-2021-3578
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2021:1170-1 No score

Security update for isync

This update for isync fixes the following issues:

Update to version 1.3.6

  • This is a security release that fixes CVE-2021-3578.
Record
openSUSE-SU-2021:1170-1
Updated
2026-11-02
OSVopenSUSE-SU-2021:1185-1 No score

Security update for isync

This update for isync fixes the following issues:

Update to version 1.3.6

  • This is a security release that fixes CVE-2021-3578.

This update was imported from the openSUSE:Leap:15.2:Update update project.

Record
openSUSE-SU-2021:1185-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:10866-1 No score

isync-1.4.3-1.2 on GA media

These are all security issues fixed in the isync-1.4.3-1.2 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10866-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
isync
Alpine:v3.14
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.15
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.16
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.17
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.18
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.19
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.20
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.21
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.22
 before 1.4.2-r0
1.4.2-r0
isync
Alpine:v3.23
 before 1.4.2-r0
1.4.2-r0
Show 16 moreShow less
Affected packages
PackageAffectedFixed
isync
Alpine:v3.24
 before 1.4.2-r0
1.4.2-r0
isync
Debian:12
 before 1.3.0-2.2
1.3.0-2.2
isync
Debian:13
 before 1.3.0-2.2
1.3.0-2.2
isync
Debian:14
 before 1.3.0-2.2
1.3.0-2.2
isync
Debian:9
From an advisory covering 3 CVEs
 before 1.2.1-2+deb9u1, plus listed versions
1.2.1-2
1.2.1-2+deb9u1
isync
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.1.2-1
 None known
isync
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.2.1-21.3.0-11.3.0-1build11.3.0-1ubuntu0.18.04.0
 None known
isync
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.3.0-2
 None known
isync
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.3.0-2.21.4.3-11.4.4-11.4.4-31.4.4-3ubuntu0.22.04.1
 None known
isync
Ubuntu:24.04:LTS
 All versions, plus listed versions
1.4.4-51.4.4-5build21.4.4-5build3
 None known
isync
Ubuntu:25.10
 All versions, plus listed versions
1.4.4-5build31.5.1-1ubuntu1
 None known
isync
Ubuntu:26.10
 All versions, plus listed versions
1.5.1-1ubuntu21.5.1-1ubuntu4
 None known
isync
Ubuntu:26.04:LTS
 All versions, plus listed versions
1.5.1-1ubuntu11.5.1-1ubuntu2
 None known
isync
openSUSE:Leap 15.2
 before 1.3.6-lp152.4.6.1
1.3.6-lp152.4.6.1
isync
SUSE:Package Hub 15 SP2
 before 1.3.6-bp152.4.6.1
1.3.6-bp152.4.6.1
isync
openSUSE:Tumbleweed
From an advisory covering 2 CVEs
 before 1.4.3-1.2
1.4.3-1.2

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-3578 is a high vulnerability (CVSS 7.8) in Debian Linux, published June 7, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.04%, the 64th percentile. Fixed in isync 1.4.2-r0.

References

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