Affected: RsyncProject rsync

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: Ubuntu:22.04:LTS: rsync, Ubuntu:24.04:LTS: rsync, Ubuntu:25.10: rsync, Ubuntu:26.04:LTS: rsync

Calum Hutton discovered that rsync contained a heap-based out-of-bounds read when handling file transfers. A remote attacker with read access to an rsync server could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 25.10. (CVE-2025-10158)

Batuhan Sancak, Damien Neil, and Michael Stapelberg discovered that rsync daemons configured without chroot protection were exposed to a race condition on parent path components. A local attacker with write access to a module could possibly use this issue to overwrite files, obtain sensitive information, or escalate privileges. (CVE-2026-29518)

It was discovered that rsync did not properly validate a length value while sorting extended attributes. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-41035)

It was discovered that rsync performed reverse-DNS lookups after chrooting in some daemon configurations. A remote attacker could possibly use this issue to bypass hostname-based access controls and access network services. (CVE-2026-43617)

Omar Elsayed discovered that rsync did not properly check for integer overflows while decoding compressed tokens. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-43618)

Andrew Tridgell discovered that rsync did not fully fix a symlink race condition in path-based system calls for daemons configured without chroot protection. A local attacker could po…