RsyncProject rsync up to 3.4.4 Size Argument Parsing parse_size_arg out-of-bounds write

Summaryinfo

A vulnerability described as critical has been identified in RsyncProject rsync up to 3.4.4. Affected by this issue is the function parse_size_arg of the component Size Argument Parsing. Executing a manipulation can lead to out-of-bounds write. This vulnerability is tracked as CVE-2026-70457. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in RsyncProject rsync up to 3.4.4 and classified as critical. This vulnerability affects the function parse_size_arg of the component Size Argument Parsing. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-70457 since 08/04/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 335063 (Linux Distros Unpatched Vulnerability : CVE-2026-70457), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.5.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (335063). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• File Transfer Software

Vendor

• RsyncProject

Name

• rsync

Version

• 3.4.0
• 3.4.1
• 3.4.2
• 3.4.3
• 3.4.4

Website

• Product: https://github.com/RsyncProject/rsync/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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