rsync 3.5.0 rrsync TOCTOU: symlink escape & unsafe flag abuse
CVE-2026-53783 Published on August 13, 2026
rsync < 3.5.0 TOCTOU Race Condition Directory Escape via rrsync
rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.
Vulnerability Analysis
CVE-2026-53783 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Types
What is an insecure temporary file Vulnerability?
The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
CVE-2026-53783 has been classified to as an insecure temporary file vulnerability or weakness.
What is an Argument Injection Vulnerability?
The software constructs a string for a command to executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
CVE-2026-53783 has been classified to as an Argument Injection vulnerability or weakness.
Products Associated with CVE-2026-53783
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Affected Versions
RsyncProject rsync:- Before and including 3.4.4 is affected.
- Version 3.5.0 is unaffected.