CVE-2026-70458
Received Received - Intake

rsync Out-of-Bounds Write in File Handling

Publication date: 2026-08-13

Last updated on: 2026-08-13

Assigner: VulnCheck

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.

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Meta Information

Published
2026-08-13
Last Modified
2026-08-13
Generated
2026-08-13
AI Q&A
2026-08-13
EPSS Evaluated
N/A
NVD
CVE-2026-70458
EUVD
EUVD-2026-58046

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.

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Executive Summary

This is an out-of-bounds write vulnerability in rsync versions 3.0.0 through 3.4.4. It occurs when processing file entries marked with FLAG_HLINKED while the hard-link preservation option is inactive. Attackers exploit a missing field in the file structure to write data beyond allocated memory, corrupting adjacent heap or stack memory.

Detection Guidance

To detect this vulnerability, check the installed rsync version on your system. Run 'rsync --version' and verify if it falls within versions 3.0.0 through 3.4.4. If so, the system is vulnerable. Monitor network traffic for rsync protocol-30 sessions with --checksum enabled and no -H flag, as these conditions are required for exploitation.

Impact Analysis

An attacker could exploit this to corrupt memory, potentially causing crashes, data corruption, or arbitrary code execution. The attack requires specific conditions like protocol-30, incremental recursion, and the --checksum option without the -H flag. It does not need privileges or user interaction.

Mitigation Strategies

Immediately upgrade rsync to version 3.5.0 or later. If upgrading is not possible, disable rsync services or restrict network access to rsync ports. Avoid using --checksum with untrusted peers and ensure the -H flag is not disabled during transfers.

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