# CVE-2026-50106: When NLnet Labs Unbound up to and including version 1.26.1 is configured with both a root trust anchor and an additional 'trust-anchor:' for


- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 21 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** AZL-110531, DEBIAN-CVE-2026-50106, ECHO-2c39-6a3d-2a23, GHSA-pj55-6fvm-845h, UBUNTU-CVE-2026-50106

## What is CVE-2026-50106?

CVE-2026-50106 is a medium-severity vulnerability in NLnet Labs Unbound, published on 21 Oct 2026. 

### Official description

When NLnet Labs Unbound up to and including version 1.26.1 is configured with both a root trust anchor and an additional 'trust-anchor:' for an island-of-security zone whose parent is provably insecure under the root chain, a malicious actor who can deliver one forged NXDOMAIN response for a name inside the island, with the NSEC/SOA RRSIG 'SignerName' set to the insecure parent, tricks Unbound's validator to use the root trust anchor instead, and consecutively the insecure parent, thus causing that record to be treated as insecure and denying existence for records in the trust island.

Weakness: CWE-807 (Reliance on Untrusted Inputs in a Security Decision)

## Which versions are affected by CVE-2026-50106?


## How do I fix CVE-2026-50106?

Upgrade to a fixed version.

## Is CVE-2026-50106 being exploited?

There is no known exploitation of CVE-2026-50106 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50106 and fix it if it is affected.

What it is: CVE-2026-50106 is a medium-severity vulnerability in NLnet Labs Unbound, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-50106 in the wild and no public exploit code.

Affected product: NLnet Labs Unbound. 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-2026-50106/ (Markdown: https://insights.sbomify.com/CVE-2026-50106/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50106
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50106
- OSV: https://osv.dev/vulnerability/CVE-2026-50106

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50106/
Summaries are generated and may contain mistakes; the official description above is the record.