# CVE-2016-6329: Weak cryptography in n/a

> Remote attackers can recover cleartext data from long-duration OpenVPN sessions using 64-bit block ciphers via a birthday attack.

- **Severity:** Medium 5.9 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/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:** 31 Jan 2017
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-w6pr-cm6j-f384, MGASA-2016-0304, UBUNTU-CVE-2016-6329

## What is CVE-2016-6329?

CVE-2016-6329 is a medium-severity vulnerability in n/a, published on 31 Jan 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a "Sweet32" attack.

Weakness: CWE-310, CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2016-6329?

It affects 1 product.


Products: Openvpn Openvpn.

## How do I fix CVE-2016-6329?

Change a configuration setting.

## Is CVE-2016-6329 being exploited?

There is no known exploitation of CVE-2016-6329 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2025-12106](https://insights.sbomify.com/CVE-2025-12106/): Memory corruption in OpenVPN (critical 9.1)
- [CVE-2024-5594](https://insights.sbomify.com/CVE-2024-5594/): Information disclosure in OpenVPN (critical 9.1)
- [CVE-2018-7544](https://insights.sbomify.com/CVE-2018-7544/): Cross-site request forgery in n/a (critical 9.1)
- [CVE-2006-1629](https://insights.sbomify.com/CVE-2006-1629/): Code injection in n/a (critical 9.0)
- [CVE-2024-4877](https://insights.sbomify.com/CVE-2024-4877/): Privilege escalation in OpenVPN (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-6329 and fix it if it is affected.

What it is: CVE-2016-6329 is a medium-severity vulnerability in n/a, published on 31 Jan 2017. 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-2016-6329 in the wild and no public exploit code.

Affected product: n/a. 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-2016-6329/ (Markdown: https://insights.sbomify.com/CVE-2016-6329/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-6329
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-6329
- OSV: https://osv.dev/vulnerability/CVE-2016-6329

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-6329/
Summaries are generated and may contain mistakes; the official description above is the record.