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.
References (3)
Core 3
Core References
Vendor Advisory vendor-advisory
https://github.com/RsyncProject/rsync/security/advisories/GHSA-8f85-j2cv-59m8
Release Notes release-notes
https://github.com/RsyncProject/rsync/releases/tag/v3.4.3
Third Party Advisory third-party-advisory
https://www.vulncheck.com/advisories/rsync-off-by-one-stack-write-via-http-proxy
Scores
CVSS v3
3.1
EPSS
0.0004
EPSS Percentile
12.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-193
Status
published
Products (2)
RsyncProject/rsync
< 3.4.3
samba/rsync
< 3.4.3
Published
May 20, 2026
Tracked Since
May 20, 2026