Bypass of a configured island trust anchor underneath an insecure parent from an atacker-controlled NSEC record. (NLnet Labs Unbound)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.11 % · percentile 1 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- NLnet Labs
- NVD status
- Awaiting Analysis
Description
When NLnet Labs Unbound 1.0.1 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 with a forged NSEC reply with the SOA bit cleared can trick Unbound to treat the configured trust island as insecure. This happens because the DNSSEC validator in Unbound accepts and caches the NSEC insecure response bypassing the RRSIG validation that the validator was supposed to do. The acceptance of the NSEC record at the trust anchor apex was allowed due to and old fix for type DS and NSEC queries from clients when trust anchor for that name existed.
Weaknesses (CWE)
- CWE-354 — Improper Validation of Integrity Check Value
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | NLnet Labs |
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | NVD · sep@nlnetlabs.nl (Secondary) |
European references
- ENISA EUVD · EUVD-2026-107151
- GCVE · GCVE-0-2026-35501
Affected products
| Product | Versions |
|---|---|
| NLnet Labs · Unbound | affected 1.0.1 < 1.26.2 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |