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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-44687 Detail

Description

In NLnet Labs Unbound 1.13.2 up to and including 1.25.1, stub or forward zones where the name is below an intermediate labed below a DNSSEC signed zone could be shadowed by the intermediate label's secure NXDOMAIN answer from the parent. This is caused by an off-by-one error in 'harden-below-nxdomain' logic; enabled by default. It effectively bypasses the configuration and the configured stub/forward zone is never contacted. 'harden-below-nxdomain' does an upward DNS cache walk together with a delegation point guard that does not allow NXDOMAIN synthesis above stub/forward zones. The guard tests the domain name but before stripping a label. This results in an iteration where the domain name equals the configured stub/forward zone apex that passes the guard, strips one more label, and probes the cache at the apex's immediate public parent. If that parent has a cached DNSSEC-secure NXDOMAIN, which it will for any private namespace nested two or more labels under a signed public name, the walk returns it and the configured stub/forward upstream is never contacted. This can only be triggered by the query for the intermediate label (between the stub/forward apex and the DNSSEC parent zone).


Metrics

 
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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44687.txt NLnet Labs

Weakness Enumeration

CWE-ID CWE Name Source
CWE-193 Off-by-one Error NLnet Labs  

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-44687
NVD Published Date:
07/22/2026
NVD Last Modified:
07/22/2026
Source:
NLnet Labs