CVE-2026-29518
Published: May 21, 2026Last modified: May 25, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7 |
| Attack Vector | LOCAL |
| Attack complexity | HIGH |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | rsync | Fixed (3.4.3-r0) |
| 25 LTS | rsync | Fixed (3.4.3-r0) | |
| Stream | rsync | Fixed (3.4.3-r0) |
References
- https://github.com/RsyncProject/rsync/pull/895/changes/8471fdd1561049ef5f58df44a1811a50bd9a531d
- https://github.com/RsyncProject/rsync/releases/tag/v3.4.3
- 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