# GHSA-6f2x-v7q7-m7m5: hickory-resolver follows irrelevant CNAME records

> The Hickory DNS resolver library sends unnecessary queries for irrelevant CNAME records, enabling query amplification and potential denial of service.

- **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:** 5 Oct 2026

## What is GHSA-6f2x-v7q7-m7m5?

GHSA-6f2x-v7q7-m7m5 is a denial of service vulnerability in hickory-resolver, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When the Hickory DNS resolver follows CNAME records, it sends queries that are not necessary to answer the original recursive query. If there are any CNAME records in the authority section or additional section of the response, queries will be sent for those names. If there are any CNAME records that are not part of a CNAME chain starting from the original recursive query name, queries will be sent for those names. This increases query amplification beyond what is necessary to answer the recursive query.

## Which versions are affected by GHSA-6f2x-v7q7-m7m5?

2 open source packages ship an affected version, including hickory-resolver.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hickory-resolver` | crates.io | From 0.25.0 | 0.26.2 |
| `hickory-resolver` | crates.io | From 0.25.0 | 0.26.2 |

## How do I fix GHSA-6f2x-v7q7-m7m5?

Upgrade hickory-resolver to 0.26.2 or later.

## Is GHSA-6f2x-v7q7-m7m5 being exploited?

There is no known exploitation of GHSA-6f2x-v7q7-m7m5 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-6f2x-v7q7-m7m5 and fix it if it is affected.

What it is: GHSA-6f2x-v7q7-m7m5 is a denial of service vulnerability in hickory-resolver, published on 5 Oct 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 GHSA-6f2x-v7q7-m7m5 in the wild and no public exploit code.

Affected packages and fixed versions:
- hickory-resolver (crates.io): affected from 0.25.0; fixed in 0.26.2
- hickory-resolver (crates.io): affected from 0.25.0; fixed in 0.26.2

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/GHSA-6f2x-v7q7-m7m5/ (Markdown: https://insights.sbomify.com/GHSA-6f2x-v7q7-m7m5/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-6f2x-v7q7-m7m5

---
From sbomify Insights: https://insights.sbomify.com/GHSA-6f2x-v7q7-m7m5/
Summaries are generated and may contain mistakes; the official description above is the record.