CVE-2026-81642

CRITICAL CVSS 4.0: 9.1 EPSS 0.96%
Updated Sep 22, 2026
Nlnetlabs
Parameter Value
CVSS 9.1 (CRITICAL)
Affected Versions before 1.26.1
Fixed In 1.26.1
Type CWE-122 (Heap-based Buffer Overflow)
Vendor Nlnetlabs
Public PoC No

In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in the DNSSEC validator that enables denial of service and possible remote code execution as a result of digesting DNSKEYs. A DNSKEY with an owner compression pointer to its own RDATA can overflow the digest buffer. Remote code execution is possible through attacker controlled data.

An adversary can exploit the vulnerability by controlling a malicious zone and querying a vulnerable Unbound.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Nlnetlabs Unbound
cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
— 1.26.1