# CVE-2026-53786: rsync < 3.5.0 Filter Rule Bypass via --filter Merge Directive

> Authenticated clients can bypass rsync module filter restrictions via malicious merge directives, accessing restricted files.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** ALPINE-CVE-2026-53786, AZL-95822, BELL-CVE-2026-53786, DEBIAN-CVE-2026-53786, ECHO-cc28-5bd9-6cca, GHSA-mrc3-6cwx-hch6, UBUNTU-CVE-2026-53786

## What is CVE-2026-53786?

CVE-2026-53786 is a medium-severity vulnerability in RsyncProject rsync, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

rsync before 3.5.0 contains a filter rule bypass vulnerability that allows authenticated clients to override module-level filter restrictions by supplying malicious --filter merge file directives. Attackers can inject client-side merge file directives during filter evaluation to introduce rules that supersede daemon module-level restrictions, gaining access to files the module filter was intended to exclude.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-53786?

It affects 1 product.


Products: Samba Rsync.

## How do I fix CVE-2026-53786?

Upgrade to a fixed version.

## Is CVE-2026-53786 being exploited?

There is no known exploitation of CVE-2026-53786 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-2026-53786 and fix it if it is affected.

What it is: CVE-2026-53786 is a medium-severity vulnerability in RsyncProject rsync, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53786 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-2026-53786/ (Markdown: https://insights.sbomify.com/CVE-2026-53786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53786
- OSV: https://osv.dev/vulnerability/CVE-2026-53786

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53786/
Summaries are generated and may contain mistakes; the official description above is the record.