# CVE-2018-5735: Backport of the fix for CVE-2017-3137 leads to assertion failure in validator.c:1858

> A regression in Debian's BIND9 backport causes an assertion failure, leading to a denial of service for DNS services.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Oct 2019
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2018-5735, DLA-1285-1, GHSA-qp2w-qqh3-4x36

## What is CVE-2018-5735?

CVE-2018-5735 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 30 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Debian backport of the fix for CVE-2017-3137 leads to assertion failure in validator.c:1858; Affects Debian versions 9.9.5.dfsg-9+deb8u15; 9.9.5.dfsg-9+deb8u18; 9.10.3.dfsg.P4-12.3+deb9u5; 9.11.5.P4+dfsg-5.1 No ISC releases are affected. Other packages from other distributions who did similar backports for the fix for 2017-3137 may also be affected.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2018-5735?

It affects 1 product.


Products: Debian Debian Linux.

## How do I fix CVE-2018-5735?

Apply the vendor's patch.

## Is CVE-2018-5735 being exploited?

There is no known exploitation of CVE-2018-5735 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-2018-5735 and fix it if it is affected.

What it is: CVE-2018-5735 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 30 Oct 2019. 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-2018-5735 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-2018-5735/ (Markdown: https://insights.sbomify.com/CVE-2018-5735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-5735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-5735
- OSV: https://osv.dev/vulnerability/CVE-2018-5735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-5735/
Summaries are generated and may contain mistakes; the official description above is the record.