# CVE-2026-123571: Hickory DNS from 0.26.0 before 0.26.2 Panic via TSIG RDATA Decoding


- **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:** 8 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-123571, GHSA-p8hx-6263-88h9, GHSA-x962-5xwx-fr8x, RUSTSEC-2026-0488, UBUNTU-CVE-2026-123571

## What is CVE-2026-123571?

CVE-2026-123571 is a high-severity vulnerability in hickory-dns, published on 8 Nov 2026. 

### Official description

Hickory DNS from 0.26.0 before 0.26.2 contains an integer underflow vulnerability in TSIG RDATA decoding that allows remote attackers to trigger a panic via malformed records. Attackers can send a crafted TSIG record in DNS wire format to cause unchecked subtraction underflow, crashing builds with overflow checks enabled and causing denial of service.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-123571?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hickory-proto` | crates.io | From 0.26.0 | 0.26.2 |

## How do I fix CVE-2026-123571?

Upgrade hickory-proto to 0.26.2 or later.

## Is CVE-2026-123571 being exploited?

There is no known exploitation of CVE-2026-123571 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123571 and fix it if it is affected.

What it is: CVE-2026-123571 is a high-severity vulnerability in hickory-dns, published on 8 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123571 in the wild and no public exploit code.

Affected packages and fixed versions:
- hickory-proto (crates.io): affected from 0.26.0; 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-2026-123571/ (Markdown: https://insights.sbomify.com/CVE-2026-123571/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123571
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123571
- OSV: https://osv.dev/vulnerability/CVE-2026-123571

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123571/
Summaries are generated and may contain mistakes; the official description above is the record.