# CVE-2026-123570: Hickory DNS from 0.18 before 0.26.2 Memory Amplification DoS via RR Counts


- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 8 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** AZL-113197, DEBIAN-CVE-2026-123570, GHSA-67wc-6jq8-ghrc, GHSA-6rvc-hrvg-mqf2, RUSTSEC-2026-0491, UBUNTU-CVE-2026-123570

## What is CVE-2026-123570?

CVE-2026-123570 is a high-severity vulnerability in hickory-dns, published on 8 Nov 2026. 

### Official description

The DNS wire-format message parser in hickory-proto (Hickory DNS) 0.18 before 0.26.2 preallocates record vectors sized by the untrusted ANCOUNT, NSCOUNT, and ARCOUNT header fields before reading record data. Remote attackers can send a UDP datagram, or a spoofed response to a client/resolver, with these counts set to 65535, forcing about 18MB of allocation per message.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-123570?

1 open source package ship an affected version, including hickory-proto.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hickory-proto` | crates.io | From 0.18.0 | 0.26.2 |

## How do I fix CVE-2026-123570?

Upgrade hickory-proto to 0.26.2 or later.

## Is CVE-2026-123570 being exploited?

There is no known exploitation of CVE-2026-123570 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123570 and fix it if it is affected.

What it is: CVE-2026-123570 is a high-severity vulnerability in hickory-dns, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123570 in the wild and no public exploit code.

Affected packages and fixed versions:
- hickory-proto (crates.io): affected from 0.18.0; 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/CVE-2026-123570/ (Markdown: https://insights.sbomify.com/CVE-2026-123570/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123570
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123570
- OSV: https://osv.dev/vulnerability/CVE-2026-123570

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123570/
Summaries are generated and may contain mistakes; the official description above is the record.