# CVE-2026-29518: Rsync < 3.4.3 TOCTOU Race Condition Allows Symlink-Based Arbitrary File Write

> Attackers can exploit a race condition in Rsync to write arbitrary files and escalate privileges if chroot is disabled.

- **Severity:** High 7.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 May 2026
- **Updated:** 1 Sep 2026
- **Also known as:** ALPINE-CVE-2026-29518, AZL-87012, BELL-CVE-2026-29518, CLSA-2026-1779694338, CLSA-2026-1779694460, CLSA-2026-1779694727, CLSA-2026-1779694887, CLSA-2026-1779746464, CLSA-2026-1779746676, CLSA-2026-1779747925, CLSA-2026-1779822401, CLSA-2026-1780480701, CLSA-2026-1780513862, DEBIAN-CVE-2026-29518, ECHO-f2d1-e04b-c5e8, GHSA-pfv9-gp3h-73xv, JLSEC-2026-626, UBUNTU-CVE-2026-29518

## What is CVE-2026-29518?

CVE-2026-29518 is a high-severity vulnerability in RsyncProject rsync, published on 20 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### 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.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-29518?

It affects 1 product.


Products: Samba Rsync.

## How do I fix CVE-2026-29518?

Upgrade to a fixed version.

## Is CVE-2026-29518 being exploited?

There is no known exploitation of CVE-2026-29518 in the wild and no public exploit code.

## Other vulnerabilities in RsyncProject rsync

- [CVE-2017-15994](https://insights.sbomify.com/CVE-2017-15994/): Security feature bypass in n/a (critical 9.8)
- [CVE-2026-53791](https://insights.sbomify.com/CVE-2026-53791/): rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header (critical 9.1)
- [CVE-2026-70461](https://insights.sbomify.com/CVE-2026-70461/): rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry (high 8.8)
- [CVE-2026-70455](https://insights.sbomify.com/CVE-2026-70455/): rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion (high 8.7)
- [CVE-2026-70463](https://insights.sbomify.com/CVE-2026-70463/): rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29518 and fix it if it is affected.

What it is: CVE-2026-29518 is a high-severity vulnerability in RsyncProject rsync, published on 20 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-29518 in the wild and no public exploit code.

Affected product: RsyncProject rsync. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-29518/ (Markdown: https://insights.sbomify.com/CVE-2026-29518/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29518
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29518
- OSV: https://osv.dev/vulnerability/CVE-2026-29518

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29518/
Summaries are generated and may contain mistakes; the official description above is the record.