CyberRota Analysis
AI-GeneratedUnbound versions 1.18.0 through 1.25.1 are vulnerable when configured to listen on a proxy-protocol-port with 'answer-cookie: yes', as the server-cookie is incorrectly computed using the proxy's wire address instead of the declared client address. This flaw allows an off-path attacker to harvest a valid server cookie with a single legitimate query and subsequently replay it from any spoofed source, bypassing DNS Cookie protections. Organizations using affected versions of Unbound in environments where proxy protocols are employed should prioritize patching to mitigate potential exploitation.
Original NVD Description
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.
Related CVEs
Other vulnerabilities affecting the same vendor(s)