Remote memory corruption via truncated size formatting
Published Aug 13, 2026 · Updated Aug 13, 2026
Out-of-bounds write in rsync 3.2.3 through 3.4.4 allows remote attackers to corrupt process memory through oversized size options. parse_size_arg() uses snprintf()'s would-have-been length after truncation as an unchecked index into the static err_buf array, causing a fixed newline and NUL write beyond the array. A daemon peer can forward the triggering options without authentication, but only the write offset is controlled and no useful security-sensitive target has been demonstrated.
Summary
What happened
Out-of-bounds write in rsync 3.2.3 through 3.4.4 allows remote attackers to corrupt process memory through oversized size options. parse_size_arg() uses snprintf()'s would-have-been length after truncation as an unchecked index into the static err_buf array, causing a fixed newline and NUL write beyond the array. A daemon peer can forward the triggering options without authentication, but only the write offset is controlled and no useful security-sensitive target has been demonstrated.
The record
- CVE
- CVE-2026-70457
- Published
- Aug 13, 2026
- Updated
- Aug 13, 2026
- Vendor
- Rsync Project
- Product
- rsync
- Classifications
- CWE-131, CWE-787, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 13, 2026CVE publishedPublication date reported by the CVE source.
- Aug 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3.2.3 <=3.4.4
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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