Description
rsync 3.4.2 before 3.5.0 contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive's string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| RsyncProject | rsync | 3.4.2 – ≤ 3.4.4 | 3.5.0 |
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 | rsync | 3.5.0+ds1-1 | — |
| Debian 13 | rsync | 3.5.0+ds1-0+deb13u1 | — |
| Debian 12 | rsync | 3.5.0+ds1-0+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | rsync | No fix yet | — |
| Ubuntu 26.04 LTS | rsync | No fix yet | — |
| Ubuntu 24.04 LTS | rsync | No fix yet | — |
| Ubuntu 22.04 LTS | rsync | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | rsync | No fix yet | — |
| Ubuntu Pro 18.04 LTS | rsync | No fix yet | — |
| Ubuntu Pro 16.04 LTS | rsync | No fix yet | — |
| Ubuntu Pro 14.04 LTS | rsync | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | rsync +2 | 3.5.0-3.el10_2 | RHSA-2026:67463 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | rsync +2 | 3.5.0-3.el10_2 | ALSA-2026:67463 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | rsync | 3.5.0-3.el10_2 | RLSA-2026:67463 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | rsync | 3.2.7-150600.3.24.1 | SUSE-SU-2026:3657-1 |
| SLES 15 SP6 | rsync | 3.2.7-150600.3.24.1 | SUSE-SU-2026:3657-1 |
| SLES 15 SP5 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLES 15 SP4 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | rsync | 3.4.1-160000.6.1 | SUSE-SU-2026:23323-1 |
| SLES for SAP 15 SP6 | rsync | 3.2.7-150600.3.24.1 | SUSE-SU-2026:3657-1 |
| SLES for SAP 15 SP5 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLES for SAP 15 SP4 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLES 16.0 | rsync | 3.4.1-160000.6.1 | SUSE-SU-2026:23323-1 |
| SLE Micro 6.2 | rsync | 3.4.1-160000.6.1 | SUSE-SU-2026:23289-1 |
| SLE Micro 6.1 | rsync | 3.3.0-slfo.1.1_7.1 | SUSE-SU-2026:23254-1 |
| SLE Micro 6.0 | rsync | 3.2.7-8.1 | SUSE-SU-2026:23253-1 |
| SLE Micro 5.5 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLE Micro 5.4 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLE Micro 5.3 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLE HPC 15 SP5 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
| SLE HPC 15 SP4 | rsync | 3.2.3-150400.3.34.1 | SUSE-SU-2026:3634-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | rsync | 3.5.1-1.1 | openSUSE-SU-2026:11869-1 |
| openSUSE Leap 16.0 | rsync | 3.4.1-160000.6.1 | openSUSE-SU-2026:21650-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | rsync | 3.5.0-r0 | — |
| Alpine v3.23 | rsync | 3.5.0-r0 | — |
| Alpine v3.22 | rsync | 3.5.0-r0 | — |
| Alpine v3.21 | rsync | 3.5.0-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | rsync | 3.5.0-1 | — |
Advisories 12
- WID-SEC-2026-2817 Rsync: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- ALSA-2026:67463 Important: rsync security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:67463 Red Hat Security Advisory: rsync security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Oct 10, 2026
- openSUSE-SU-2026:11869-1 rsync-3.5.1-1.1 on GA media SUSE / openSUSE Security Updates · Sep 24, 2026
- RLSA-2026:67463 Important: rsync security, bug fix, and enhancement update Rocky Linux Security Advisories · Sep 15, 2026
- SUSE-SU-2026:23323-1 Security update for rsync SUSE / openSUSE Security Updates · Sep 10, 2026
- SUSE-SU-2026:23289-1 Security update for rsync SUSE / openSUSE Security Updates · Sep 4, 2026
- SUSE-SU-2026:23254-1 Security update for rsync SUSE / openSUSE Security Updates · Aug 31, 2026
- SUSE-SU-2026:23253-1 Security update for rsync SUSE / openSUSE Security Updates · Aug 27, 2026
- openSUSE-SU-2026:21650-1 Security update for rsync SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:3657-1 Security update for rsync SUSE / openSUSE Security Updates · Aug 21, 2026
- SUSE-SU-2026:3634-1 Security update for rsync SUSE / openSUSE Security Updates · Aug 18, 2026
References
- GitHub Security Advisory (GHSA-rjvj-qgqg-cvx9) vendor-advisory
- rsync 3.5.0 Release Notes release-notes
- https://www.vulncheck.com/advisories/rsync-dos-via-zt-zstandard-compression-thread-exhaustion third-party-advisory