CVE-2026-44687 Affecting unbound-devel package, versions <1.25.2-150600.23.19.1


Severity

Recommended
medium

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.22% (12th percentile)

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  • Snyk IDSNYK-SLES156-UNBOUNDDEVEL-19680965
  • published11 Sept 2026
  • disclosed31 Aug 2026

Introduced: 31 Aug 2026

CVE-2026-44687  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 unbound-devel to version 1.25.2-150600.23.19.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream unbound-devel package and not the unbound-devel package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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).

CVSS Base Scores

version 3.1