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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | isync | isync 1.3.6, isync 1.4.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | isync | 1.3.0-2.2 | — |
| Debian 13 | isync | 1.3.0-2.2 | — |
| Debian 12 | isync | 1.3.0-2.2 | — |
| Debian 9 | isync | 1.2.1-2+deb9u1 | DLA-3066-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | isync | No fix yet | — |
| Ubuntu 26.04 LTS | isync | No fix yet | — |
| Ubuntu 25.10 | isync | No fix yet | — |
| Ubuntu 24.04 LTS | isync | No fix yet | — |
| Ubuntu 22.04 LTS | isync | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | isync | No fix yet | — |
| Ubuntu 18.04 LTS | isync | No fix yet | — |
| Ubuntu 16.04 LTS | isync | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP2 | isync | 1.3.6-bp152.4.6.1 | openSUSE-SU-2021:1185-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | isync | 1.4.3-1.2 | openSUSE-SU-2024:10866-1 |
| openSUSE Leap 15.2 | isync | 1.3.6-lp152.4.6.1 | openSUSE-SU-2021:1170-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | isync | 1.4.2-r0 | — |
| Alpine v3.23 | isync | 1.4.2-r0 | — |
| Alpine v3.22 | isync | 1.4.2-r0 | — |
| Alpine v3.21 | isync | 1.4.2-r0 | — |
| Alpine v3.20 | isync | 1.4.2-r0 | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | isync | 1.4.2-r0 | — |
| Alpine v3.18 | isync | 1.4.2-r0 | — |
| Alpine v3.17 | isync | 1.4.2-r0 | — |
| Alpine v3.16 | isync | 1.4.2-r0 | — |
| Alpine v3.15 | isync | 1.4.2-r0 | — |
| Alpine v3.14 | isync | 1.4.2-r0 | — |
Advisories 4
- DLA-3066-1 isync - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2021:1185-1 Security update for isync SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10866-1 isync-1.4.3-1.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1170-1 Security update for isync SUSE / openSUSE Security Updates · Feb 4, 2026
References
- [oss-security] 20210607 CVE-2021-3578: possible remote code execution in isync/mbsync mailing-list
- FEDORA-2021-f236f9f01a vendor-advisory
- FEDORA-2021-754af4d52b vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1961710
- https://github.blog/2021-06-10-privilege-escalation-polkit-root-on-linux-with-bug/
- https://bugzilla.redhat.com/show_bug.cgi?id=1967397
- https://www.openwall.com/lists/oss-security/2021/06/07/1
- [debian-lts-announce] 20220701 [SECURITY] [DLA 3066-1] isync security update mailing-list
- GLSA-202208-15 vendor-advisory