CVE-2026-81634

A flaw was found in Unbound. This vulnerability allows a remote attacker to cause a heap buffer overflow during the processing of DNSSEC responses. By sending a specially crafted DNSSEC response, a malicious server or an attacker tampering with network traffic can trigger this flaw. This could lead to a denial of service, making the Unbound service unavailable.

This is an Important flaw where Unbound, when acting as a recursive DNS resolver, is vulnerable to a heap buffer overflow. A remote attacker could exploit this by operating a malicious name server or by intercepting and manipulating DNS responses, potentially leading to a denial of service or arbitrary code execution. This risk is heightened in deployments where Unbound processes queries from untrusted sources.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.