Security Advisory

CVE-2026-81634

CVE vulnerability detail - eXtreme Datacenter Security Operations

Published 2026-09-16 08:30:15

Last updated 2026-09-16 14:32:38

Assigner NLnet Labs

CVSS score 7.5

State PUBLISHED

Description

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.

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