CVE-2026-50106 (CVSS 6.5)

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.

Is your site exposed to CVE-2026-50106?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-807 CWE-807

References

Other References

https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50106.txt

Frequently Asked Questions

What is 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 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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-50106? +

CVE-2026-50106 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-50106? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-79701

Joomla Extension - joomshaper.com - Unauthenticated CAPTCHA Bypass in Module Context in the Contact, Opt-in and Form Builder Addons in …

CVE-2026-39807

Reliance on Untrusted Inputs in a Security Decision vulnerability in mtrudel bandit allows unauthenticated transport-state spoofing on plaintext HTTP connections. …

CVE-2025-0117

A reliance on untrusted input for a security decision in the GlobalProtect app on Windows devices potentially enables a locally …

CVE-2026-76147

A path traversal (ZIP Slip) vulnerability caused by insufficient authorization and integrity verification in the agent upgrade feature of Genian …

CVE-2026-9561

Eclipse Kura versions prior to 5.6.2 trust the client-supplied X-Forwarded-For HTTP header as the authoritative source of the client IP …

CVE-2026-103923

KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web. From 0.11.0 until 0.18.2, KaTeX uses …

CVE-2026-50106