Description
rsync before 3.5.2 contains a denial of service vulnerability in the delta-transfer sender's hash_search() in match.c that allows malicious receivers to trigger unbounded strong-checksum work at consecutive offsets. Unauthenticated attackers pulling from a public daemon module can supply weak checksums colliding with consecutive rolling windows plus non-matching strong checksums, exhausting sender CPU across concurrent connections.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| RsyncProject | rsync | ≤ 3.5.1 | 3.5.2 |
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 | rsync | 3.5.2+ds1-1 | — |
| Debian 13 | rsync | No fix yet | — |
| 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 10.2 EUS | rsync +2 | 3.5.0-3.el10_2.1 | RHSA-2026:99576 |
| Red Hat Hardened Images 1 | rsync +2 | 3.5.1-1.1.hum1 | RHSA-2026:94806 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | rsync | 3.5.2-1.1 | openSUSE-SU-2026:12443-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | rsync | 3.5.2-r0 | — |
| Alpine v3.23 | rsync | 3.5.2-r0 | — |
| Alpine v3.22 | rsync | 3.5.2-r0 | — |
| Alpine v3.21 | rsync | 3.5.2-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | rsync | No fix yet | — |
Advisories 4
- RHSA-2026:99576 Red Hat Security Advisory: rsync security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:94806 Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- WID-SEC-2026-4324 Rsync: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Nov 11, 2026
- openSUSE-SU-2026:12443-1 rsync-3.5.2-1.1 on GA media SUSE / openSUSE Security Updates · Nov 6, 2026
References
- Fixed Release Tag release-notes
- Pull Request #1132 patch issue-tracking
- Patch Commit patch
- https://github.com/RsyncProject/rsync/blob/a7404a9a633cff28ee1602f328b9c3fa69cdbd04/testsuite/hashsearch-collision-skip_test.py technical-description
- VulnCheck Advisory: rsync through 3.5.1 Denial of Service via hash_search() Checksum Collisions third-party-advisory