CVE-2026-70457: rsyncproject rsync Incorrect Calculation of Buffer Size

Vulnerability summary

CVE-2026-70457 is a high (CVSS 8.3) Incorrect Calculation of Buffer Size vulnerability in rsyncproject rsync. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 30.2% of scored vulnerabilities.

Timeline

1. 13-08-2026
   PublishedVulnerability first disclosed.
2. 14-08-2026
   Last modifiedVulnerability information updated.

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.

• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.