Critical Unbound DNSSEC Validator Flaw Could Allow RCE via a Malicious DNS Zone
Every release of the Unbound DNS resolver before 1.26.1 has a critical heap overflow in its DNSSEC validator, maintainer NLnet Labs said in an advisory on Wednesday. An attacker who controls a malicious zone and queries a vulnerable resolver can trigger it, enabling remote code execution. Unbound 1.26.1, released the same day, fixes the bug, tracked as CVE-2026-81642 , along with eight other flaws. One of the eight, CVE-2026-82717 , is a heap corruption bug in CNAME synthesis reported by Ben Morris of Anthropic. It could also lead to remote code execution "under certain systems and compilation options," NLnet Labs said. NLnet Labs has not reported exploitation of either bug, and CISA's entry for CVE-2026-81642 marked exploitation as "none" on Wednesday. NLnet Labs rates the DNSKEY flaw Critical, with a CVSS score of 4.0 (9.1), and its scoring lists a network attack vector requiring no privileges or user interaction. NVD listed the CVE as "Await...
Sep 17, 2026