Time-of-check Time-of-use (TOCTOU) Affecting rsync-daemon package, versions <0:3.5.1-1.amzn2023.0.1


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.12% (2nd percentile)

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  • Snyk IDSNYK-AMZN2023-RSYNCDAEMON-20246763
  • published29 Sept 2026
  • disclosed13 Aug 2026

Introduced: 13 Aug 2026

CVE-2026-53799  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 rsync-daemon to version 0:3.5.1-1.amzn2023.0.1 or higher.
This issue was patched in ALAS2023-2026-3131.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rsync-daemon package and not the rsync-daemon package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

rsync before 3.5.0 contains a symlink race condition vulnerability that allows local attackers to cause rsync to apply arbitrary ACLs or extended attributes to unintended files by substituting a symlink at a predictable destination path between the file write and the subsequent acl_set_file() or lsetxattr() call. Attackers can exploit this timing window to redirect ACL and xattr application through a crafted symlink to files outside the intended destination tree, potentially granting elevated permissions and enabling local privilege escalation.

CVSS Base Scores

version 3.1