CVE-2026-70458: rsync 3.0.0 < 3.5.0 Out-of-Bounds Write via FLAG_HLINKED Handling

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-13 · updated 2026-10-24
Weakness: CWE-787

Description

rsync 3.0.0 before 3.5.0 contains an out-of-bounds write vulnerability that allows attackers to corrupt memory by triggering HLINK_BUMP processing on file entries with the FLAG_HLINKED flag set while the hard-link preservation option is inactive. Attackers can exploit the missing F_SUM field in the file_struct layout to access memory past the end of the allocated structure, corrupting adjacent heap or stack data.

Affected products

RsyncProject rsync: from 3.0.0 through 3.4.4

References

https://github.com/RsyncProject/rsync/releases/tag/v3.5.0
https://github.com/RsyncProject/rsync/security/advisories/GHSA-gg3m-4m9m-268h
https://www.vulncheck.com/advisories/rsync-out-of-bounds-write-via-flag-hlinked-handling

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