CVE-2026-81634
HIGHCVSS 7.5Description
In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add the first owner name into the buffer length check. A malicious actor operating a malicious name server or tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can trigger the vulnerability.
Timeline
Published:September 16th, 2026 9:17 AM
Last modified:September 23rd, 2026 7:51 PM
CVSS Scoring
CVSS v3: 7.5 (HIGH)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected Software
From NVD CPE configuration data
Vendors
nlnetlabs
Products
unbound
Weaknesses (CWE)
References & Reports
Advisories, patches, and third-party reports
Source: NIST NVD · Data may lag official sources by up to one minute