{"cve":"CVE-2026-77955","nvd":{"published":"2026-09-16T09:17:05.780","modified":"2026-09-23T20:19:28.093","status":"Analyzed","description":"In NLnet Labs Unbound 1.13.2 up to and including 1.26.1, a vulnerability in ZONEMD configured zones (zonemd-check: yes) which are located below (but not at) a trust anchor allow for an attack window where (tampered with) zone contents are served (or stored to disk) prior to the ZONEMD integrity check. This is caused by the needed DS/DNSKEY asynchronous resolution that needs to happen before the ZONEMD check completes. If a zonefile is written to disk (zonefile: option) while the ZONEMD check failed, the tampered data are reloaded on startup and available until ZONEMD verification concludes again. If verification fails, the data is not served any more but still persists on disk for future reloads.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N","score":4.4},"cwes":["CWE-345"],"references":["https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-77955.txt"],"products":["nlnetlabs:unbound"],"source":"nvd","synced_at":"2026-10-19T22:54:41.405518556+00:00"},"epss":{"cve":"CVE-2026-77955","score":0.00172,"percentile":0.06616,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}