CVE-2026-77955
mediumpriority · track · 0OT risk · elevatedEPSS 0.002 · 6 %ileDEUSEPSS · scored 2026-10-22
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (13)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3392Unbound: Mehrere SchwachstellenDeutsch2026-09-15csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Unbound ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Speicher zu korrumpieren, einen Denial of Service zu verursachen oder Code auszuführen.
sources
Which sources assert this record, and when.
references (1) nvd
External citations — patches, advisories, analysis.
- https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-77955.txtPatchVendor Advisory
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