# CVE-2020-14387: Security feature bypass in rsync

> Attackers can bypass TLS host validation in rsync-ssl via man-in-the-middle attacks, compromising data confidentiality and integrity.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 May 2021
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2020-14387, AZL-7462, DEBIAN-CVE-2020-14387, GHSA-5gm2-c485-9q6q

## What is CVE-2020-14387?

CVE-2020-14387 is a high-severity vulnerability in rsync, published on 27 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in rsync in versions since 3.2.0pre1. Rsync improperly validates certificate with host mismatch vulnerability. A remote, unauthenticated attacker could exploit the flaw by performing a man-in-the-middle attack using a valid certificate for another hostname which could compromise confidentiality and integrity of data transmitted using rsync-ssl. The highest threat from this vulnerability is to data confidentiality and integrity. This flaw affects rsync versions before 3.2.4.

Weakness: CWE-297 (Improper Validation of Certificate with Host Mismatch)

## Which versions are affected by CVE-2020-14387?

It affects 1 product.


Products: Samba Rsync.

## How do I fix CVE-2020-14387?

Upgrade to a fixed version.

## Is CVE-2020-14387 being exploited?

There is no known exploitation of CVE-2020-14387 in the wild and no public exploit code.

## Other vulnerabilities in 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-2020-14387 and fix it if it is affected.

What it is: CVE-2020-14387 is a high-severity vulnerability in rsync, published on 27 May 2021. 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-2020-14387 in the wild and no public exploit code.

Affected product: 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-2020-14387/ (Markdown: https://insights.sbomify.com/CVE-2020-14387/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-14387
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-14387
- OSV: https://osv.dev/vulnerability/CVE-2020-14387

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-14387/
Summaries are generated and may contain mistakes; the official description above is the record.