Vulnerability · Published May 20, 2026 · Assigned by VulnCheck
CVE-2026-29518Rsync < 3.4.3 TOCTOU Race Condition Allows Symlink-Based Arbitrary File Write
High 7.0
In plain English
A high-severity security flaw in rsync from RsyncProject. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 4% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | rsync | 3.4.4-1.el10_2 | ALSA-2026:26332 |
| AlmaLinux:8 | rsync | 3.1.3-27.el8_10 | ALSA-2026:26408 |
| AlmaLinux:9 | rsync | 3.2.5-7.el9_8.2 | ALSA-2026:26410 |
| AlmaLinux:10 | rsync-daemon | 3.4.4-1.el10_2 | ALSA-2026:26332 |
| AlmaLinux:8 | rsync-daemon | 3.1.3-27.el8_10 | ALSA-2026:26408 |
| AlmaLinux:9 | rsync-daemon | 3.2.5-7.el9_8.2 | ALSA-2026:26410 |
| AlmaLinux:10 | rsync-rrsync | 3.4.4-1.el10_2 | ALSA-2026:26332 |
| AlmaLinux:9 | rsync-rrsync | 3.2.5-7.el9_8.2 | ALSA-2026:26410 |
| Alpine:v3.20 | rsync | 3.4.3-r0 | ALPINE-CVE-2026-29518 |
| Alpine:v3.21 | rsync | 3.4.3-r0 | ALPINE-CVE-2026-29518 |
| Alpine:v3.22 | rsync | 3.4.3-r0 | ALPINE-CVE-2026-29518 |
| Alpine:v3.23 | rsync | 3.4.3-r0 | ALPINE-CVE-2026-29518 |
| Alpine:v3.24 | rsync | 3.4.3-r0 | ALPINE-CVE-2026-29518 |
| Debian:12 | rsync | 3.2.7-1+deb12u5 | DEBIAN-CVE-2026-29518 |
| Debian:13 | rsync | 3.4.1+ds1-5+deb13u3 | DEBIAN-CVE-2026-29518 |
| Debian:14 | rsync | 3.4.3+ds1-1 | DEBIAN-CVE-2026-29518 |
| Rocky Linux:10 | rsync | 0:3.4.4-1.el10_2 | RLSA-2026:26332 |
| Rocky Linux:8 | rsync | 0:3.1.3-27.el8_10 | RLSA-2026:26408 |
| Rocky Linux:9 | rsync | 0:3.2.5-7.el9_8.2 | RLSA-2026:26410 |
| Ubuntu:22.04:LTS | rsync | 3.2.7-0ubuntu0.22.04.6 | UBUNTU-CVE-2026-29518 |
| Ubuntu:24.04:LTS | rsync | 3.2.7-1ubuntu1.4 | UBUNTU-CVE-2026-29518 |
| Ubuntu:25.10 | rsync | 3.4.1+ds1-5ubuntu1.2 | UBUNTU-CVE-2026-29518 |
| Ubuntu:26.04:LTS | rsync | 3.4.1+ds1-7ubuntu0.2 | UBUNTU-CVE-2026-29518 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RsyncProject | rsync | 0 – before 3.4.3 |
Weakness: CWE-367 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
References
- https://github.com/RsyncProject/rsync/pull/895/changes/8471fdd1561049ef5f58df44a1811a50bd9a531d issue-tracking
- 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/ technical-description
- https://www.vulncheck.com/advisories/rsync-toctou-race-condition-allows-symlink-based-arbitrary-file-write third-party-advisory
- https://access.redhat.com/security/cve/CVE-2026-29518 vdb-entry, x_refsource_REDHAT
- RHBZ#2469055 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29518.json x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:54769 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:26332 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:26410 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:26408 vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:29197 vendor-advisory, x_refsource_REDHAT