CVE-2026-70457 rsync 3.2.3 < 3.5.0 Out-of-Bounds Write via parse_size_arg()

What is CVE-2026-70457?

CVE-2026-70457 is a high-severity memory corruption vulnerability in RsyncProject rsync, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

rsync 3.2.3 before 3.5.0 contains an out-of-bounds write in parse_size_arg() where the return value of snprintf() is used directly as an index into a .bss-segment array without bounds checking. When snprintf truncates the formatted size string, the return value equals the number of characters that would have been written including the truncated portion, and this value may exceed the array length. The subsequent indexed write targets memory outside the intended array bounds, corrupting .bss memory.

Weakness: CWE-787, CWE-131

Which versions are affected by CVE-2026-70457?

It affects 1 product.

Products include Samba Rsync.

How do I fix CVE-2026-70457?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-70457 being exploited?

There is no known exploitation of CVE-2026-70457 in the wild and no public exploit code.

Other vulnerabilities in RsyncProject rsync

• CVE-2017-15994 Security feature bypass in n/a Critical 9.8
• CVE-2026-53791 rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header Critical 9.1
• CVE-2026-70461 rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry High 8.8
• CVE-2026-70455 rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion High 8.7
• CVE-2026-70463 rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing High 8.6

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2026-70457, AZL-95846, BELL-CVE-2026-70457, DEBIAN-CVE-2026-70457, ECHO-112e-6676-e997, GHSA-pg7g-xqmr-xpfh and 2 more.