# CVE-2015-3405: Weak cryptography in n/a

> Insufficient entropy in NTP key generation allows remote attackers to brute force MD5 keys, compromising authentication integrity.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/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:** 9 Aug 2017
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2015-3405, GHSA-wwx9-mwhp-g8mc, UBUNTU-CVE-2015-3405

## What is CVE-2015-3405?

CVE-2015-3405 is a high-severity vulnerability in Debian Debian Linux, published on 9 Aug 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ntp-keygen in ntp 4.2.8px before 4.2.8p2-RC2 and 4.3.x before 4.3.12 does not generate MD5 keys with sufficient entropy on big endian machines when the lowest order byte of the temp variable is between 0x20 and 0x7f and not #, which might allow remote attackers to obtain the value of generated MD5 keys via a brute force attack with the 93 possible keys.

Weakness: CWE-331 (Insufficient Entropy)

## Which versions are affected by CVE-2015-3405?

It affects 13 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Ntp Ntp, Opensuse Suse Linux Enterprise Server, Opensuse Project Suse Linux Enterprise Desktop, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux for Ibm Z Systems, Redhat Enterprise Linux for Power Big Endian, Redhat Enterprise Linux for Scientific Computing, Redhat Enterprise Linux Server, Redhat Enterprise Linux Server From Rhui 6, Redhat Enterprise Linux Workstation, Suse Suse Linux Enterprise Server.

## How do I fix CVE-2015-3405?

Upgrade to a fixed version.

## Is CVE-2015-3405 being exploited?

There is no known exploitation of CVE-2015-3405 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2015-3405 and fix it if it is affected.

What it is: CVE-2015-3405 is a high-severity vulnerability in Debian Debian Linux, published on 9 Aug 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-2015-3405 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2015-3405/ (Markdown: https://insights.sbomify.com/CVE-2015-3405/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2015-3405
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2015-3405
- OSV: https://osv.dev/vulnerability/CVE-2015-3405

---
From sbomify Insights: https://insights.sbomify.com/CVE-2015-3405/
Summaries are generated and may contain mistakes; the official description above is the record.