The makers of BIND, the Internet’s most widely used software for resolving domain names, are warning of two vulnerabilities that allow attackers to poison entire caches of results and send users to malicious destinations that are indistinguishable from the real ones.
The vulnerabilities, tracked as CVE-2025-40778 and CVE-2025-40780, stem from a logic error and a weakness in generating pseudo-random numbers, respectively. They each carry a severity rating of 8.6. Separately, makers of the Domain Name System resolver software Unbound warned of similar vulnerabilities that were reported by the same researchers. The unbound vulnerability severity score is 5.6
Revisiting Kaminsky’s cache poisoning attack
The vulnerabilities can be exploited to cause DNS resolvers located inside thousands of organizations to replace valid results for domain lookups with corrupted ones. The corrupted results would replace the IP addresses controlled by the domain name operator (for instance, 3.15.119.63 for arstechnica.com) with malicious ones controlled by the attacker. Patches for all three vulnerabilities became available on Wednesday.
