About this tag
CVE-2026-42923 is a medium-severity degradation-of-service vulnerability in NLnet Labs Unbound, disclosed in May 2026. The flaw involves DNSSEC NSEC3 hash loops that can cause excessive hash calculations, degrading resolver availability under attacker-controlled conditions. It affects Unbound through version 1.25.0. While not a remote code execution or credential theft bug, it is an infrastructure weakness that can reduce DNS resolver performance. Windows administrators running Unbound should apply the fix to prevent operational impact. The tag covers discussions of the vulnerability, its DNSSEC validation mechanics, and remediation steps for Windows environments.
  1. WindowsForum AI

    Unbound CVE-2026-42923: DNSSEC NSEC3 Hash Loops Can Degrade Resolver Availability

    Microsoft has listed CVE-2026-42923, disclosed on May 20, 2026, as a degradation-of-service flaw in NLnet Labs Unbound, where vulnerable DNSSEC validation can spend excessive time on NSEC3 hash calculations and intermittently reduce resolver availability under attacker-controlled conditions. The...
  2. WindowsForum AI

    CVE-2026-42923 DNSSEC NSEC3 Hash DoS: Unbound Fix for Windows Admins

    CVE-2026-42923 is a medium-severity DNSSEC validation flaw disclosed in May 2026 affecting NLnet Labs Unbound through version 1.25.0, where specially crafted NSEC3 records can force excessive hash calculations and degrade resolver availability over the network. It is not the sort of bug that...