CVE-2026-54478

The record

In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a given proxy node therefore validates for every PROXYv2-declared source behind that node. On a UDP+proxy-protocol front, an off-path attacker can harvest one cookie with a single legitimate query, then replay it under any spoofed source and pass DNS Cookie checks that were deployed to defeat this in the first place.

Affected packages

Related vulnerabilities

• CVE-2026-114640 Traefik from v3.7.0 before v3.7.14 contains an authentication bypass vulnerability in its… CWE-290
• CVE-2026-90711 proxy-addr is a Node.js module that determines a request's client address behind trusted… CWE-290
• CVE-2026-66674 Unauthenticated Bypass Vulnerability in Simple Cloudflare Turnstile <= 1.42.1 versions. CWE-290
• CVE-2026-82563 An attacker could impersonate the camera and place themselves in a man-in-the-middle or… CWE-290
• CVE-2026-82530 IP2Location Country Blocker plugin for WordPress before 2.45.0 contains an access control… CWE-290
• CVE-2026-77089 Command Center API contained an authentication bypass issue affecting privilege… CWE-290
• CVE-2026-86478 In JetBrains YouTrack before 2025.3.161254, 2026.1.14042 improper authentication in… CWE-290
• CVE-2026-84186 Vulnerability involving incorrect access control in the Tools::getRemoteAddr() function… CWE-290