Out-of-bounds write in Rsync - CVE-2026-70457
Published: August 13, 2026
Vulnerability identifier: #VU142271
CSH Severity: Medium
CVSS v4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-70457
CWE-ID: CWE-787
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service and modify memory.
The vulnerability exists due to an out-of-bounds write in parse_size_arg() when processing oversized size-related option values forwarded through server_options(). A remote attacker can send specially crafted --max-size, --min-size, --max-alloc, --bwlimit, or --block-size values to cause a denial of service and modify memory.
The issue results in a fixed two-byte write of newline and NUL at an attacker-chosen offset in .bss.
Affected software
Rsync
How to mitigate CVE-2026-70457
Install security update from vendor's website.
Rsync - update to 3.5.0