# GO-2026-6237: Denial of service via malformed IPv4 packet in github.com/insomniacslk/dhcp

> A remote attacker can cause a denial of service in applications using the insomniacslk/dhcp library by sending a malformed IPv4 packet.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2026

## What is GO-2026-6237?

GO-2026-6237 is a denial of service vulnerability in github.com/insomniacslk/dhcp, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In github.com/insomniacslk/dhcp/dhcpv4/nclient4, BroadcastRawUDPConn.ReadFrom does not validate that the IPv4 payload length is sufficient to hold a UDP header before calculating the DHCP payload length. A frame with an IPv4 total-length field specifying fewer than eight payload bytes results in a negative DHCP length, causing a panic in buf.Consume due to a negative slice bound.

## Which versions are affected by GO-2026-6237?

1 open source package ship an affected version, including github.com/insomniacslk/dhcp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/insomniacslk/dhcp` | Go | All versions | 0.0.0-20260719225207-c76316d4aa82 |

## How do I fix GO-2026-6237?

Upgrade github.com/insomniacslk/dhcp to 0.0.0-20260719225207-c76316d4aa82 or later.

## Is GO-2026-6237 being exploited?

There is no known exploitation of GO-2026-6237 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GO-2026-6237 and fix it if it is affected.

What it is: GO-2026-6237 is a denial of service vulnerability in github.com/insomniacslk/dhcp, published on 18 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 GO-2026-6237 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/insomniacslk/dhcp (Go): affected all versions; fixed in 0.0.0-20260719225207-c76316d4aa82

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/GO-2026-6237/ (Markdown: https://insights.sbomify.com/GO-2026-6237/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GO-2026-6237

---
From sbomify Insights: https://insights.sbomify.com/GO-2026-6237/
Summaries are generated and may contain mistakes; the official description above is the record.