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Vulnerability record · CVE-2026-29518 · published 20 May 2026

CVE-2026-29518: Samba rsync toctou race condition vulnerability

Samba · Rsync

Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect file writes outside intended directories by replacing parent directory components with symbolic links. Attackers with write access to a module path can exploit this race condition to create or overwrite arbitrary files, potentially modifying sensitive system files and achieving privilege escalation when the daemon runs with elevated privileges. This vulnerability can only be triggered if the chroot setting is false.

7.3 CVSS 4.0 High EPSS 0.14% · top 97.2% CWE-367 · TOCTOU race condition
7.3CVSS 4.0 base score
0.14%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
12References
19 Aug 2026Last modified by NVD

Description

Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect file writes outside intended directories by replacing parent directory components with symbolic links. Attackers with write access to a module path can exploit this race condition to create or overwrite arbitrary files, potentially modifying sensitive system files and achieving privilege escalation when the daemon runs with elevated privileges. This vulnerability can only be triggered if the chroot setting is false.

CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/RsyncProject/rsync/pull/895/changes/8471fdd1561049ef5f58df44a1811a50bd9a531d Patch
https://github.com/RsyncProject/rsync/releases/tag/v3.4.3 Release Notes
https://michael.stapelberg.ch/posts/2026-05-24-minimal-memory-safe-go-rsync-vulns/
https://www.vulncheck.com/advisories/rsync-toctou-race-condition-allows-symlink-based-arbitrary-file-write Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:26332
https://access.redhat.com/errata/RHSA-2026:26408
https://access.redhat.com/errata/RHSA-2026:26410
https://access.redhat.com/errata/RHSA-2026:29197
https://access.redhat.com/errata/RHSA-2026:54769
https://access.redhat.com/security/cve/CVE-2026-29518
https://bugzilla.redhat.com/show_bug.cgi?id=2469055
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29518.json

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-29518), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.