Description
Rsync versions before 3.4.3 contain an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function in socket.c that allows network attackers to corrupt stack memory by sending a malformed HTTP proxy response. Attackers can exploit this by positioning themselves between the client and proxy or controlling the proxy server to send a response line of 1023 or more bytes without a newline terminator, causing a null byte to be written to an out-of-bounds stack address when the RSYNC_PROXY environment variable is set.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| RsyncProject | rsync | < 3.4.3 | 3.4.3 |
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 | 3.4.3+ds1-1 | — |
| Debian 13 | rsync | 3.4.1+ds1-5+deb13u4 | — |
| Debian 12 | rsync | 3.2.7-1+deb12u6 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | rsync | 3.4.1+ds1-7ubuntu0.2 | — |
| Ubuntu 25.10 | rsync | 3.4.1+ds1-5ubuntu1.2 | — |
| Ubuntu 24.04 LTS | rsync | 3.2.7-1ubuntu1.4 | — |
| Ubuntu 22.04 LTS | rsync | 3.2.7-0ubuntu0.22.04.6 | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | rsync | 3.1.3-8ubuntu0.9+esm1 | — |
| Ubuntu Pro 18.04 LTS | rsync | 3.1.2-2.1ubuntu1.6+esm3 | — |
| Ubuntu Pro 16.04 LTS | rsync | 3.1.1-3ubuntu1.3+esm5 | — |
| Ubuntu Pro 14.04 LTS | rsync | 3.1.0-2ubuntu0.4+esm3 | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | rsync | 3.4.1-160000.4.1 | SUSE-SU-2026:22015-1 |
| SLES 16.0 | rsync | 3.4.1-160000.4.1 | SUSE-SU-2026:22015-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | rsync | 3.4.3-1.1 | openSUSE-SU-2026:10857-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | rsync | 3.4.3-r0 | — |
| Alpine v3.23 | rsync | 3.4.3-r0 | — |
| Alpine v3.22 | rsync | 3.4.3-r0 | — |
| Alpine v3.21 | rsync | 3.4.3-r0 | — |
| Alpine v3.20 | rsync | 3.4.3-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | rsync +1 | 3.5.1-1.amzn2023.0.1 | ALAS2023-2026-3131 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | rsync | 3.4.3-1 | — |
Advisories 5
- WID-SEC-2026-2455 Oracle Solaris Drittanbieterkomponenten: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 27, 2026
- WID-SEC-2026-1611 Rsync: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 4, 2026
- ALAS2023-2026-3131 Important: rsync security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Sep 28, 2026
- SUSE-SU-2026:22015-1 Security update for rsync SUSE / openSUSE Security Updates · Jun 9, 2026
- openSUSE-SU-2026:10857-1 rsync-3.4.3-1.1 on GA media SUSE / openSUSE Security Updates · May 25, 2026
References
- GitHub Security Advisory (GHSA-8f85-j2cv-59m8) vendor-advisory
- rsync 3.4.3 Release Notes release-notes
- https://www.vulncheck.com/advisories/rsync-off-by-one-stack-write-via-http-proxy third-party-advisory