CVE-2026-55708 Details
Description
In NLnet Labs Unbound 1.6.0 up to and including 1.25.1, the 'view_local_data' and 'view_local_datas' commands of 'unbound-control' create a bare local zones tree for an already configured named view when the view is configured with no local data to begin with. However, the creation through the control interface omits adding the default-protected zones (e.g., RFC 1918 reverse, AS112 zones, .onion, .localhost). Once the local zone tree exists without the defaults, every query for a default-protected name from a client mapped to that view escapes to the public DNS via the iterator instead of being answered locally, bypassing local policy expectations.
A vulnerability exists in NLnet Labs Unbound versions 1.6.0 through 1.25.1, where the 'view_local_data' and 'view_local_datas' commands in 'unbound-control' create a local zones tree for a named view that initially has no local data. However, this process fails to include default-protected zones, such as RFC 1918 reverse, AS112 zones, .onion, and .localhost. As a result, once the local zone tree is established without these default zones, queries for default-protected names from clients in that view are sent to public DNS instead of being resolved locally, thereby circumventing local policy expectations.
Users can upgrade to Unbound version 1.25.2, which includes the necessary fix. Alternatively, for those using Unbound 1.25.1, a patch is available that can be applied manually. After applying the patch, Unbound should be recompiled and installed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 22, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-55708.txt | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1188 | Initialization of a Resource with an Insecure Default | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| nlnetlabs unbound | >= 1.6.0, < 1.25.2 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 24, 2026 | Initial Analysis | [email protected] |
| Jul 22, 2026 | CVE Modified | CISA-ADP |
| Jul 22, 2026 | New CVE Received | [email protected] |