pdns-recursor: Cache pollution (CVE-2020-25829)

An issue has been found in PowerDNS Recursor where a remote attacker can cause the cached records for a given name to be updated to the ‘Bogus’ DNSSEC validation state, instead of their actual DNSSEC ‘Secure’ state, via a DNS ANY query. This results in a denial of service for installations that always validate (dnssec=validate) and for clients requesting validation when on-demand validation is enabled (dnssec=process).

Affects: PowerDNS Recursor up to and including 4.3.4, 4.2.4 and 4.1.17

Not affected: 4.3.5, 4.2.5, 4.1.18

References:

• https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2020-07.html
• https://www.openwall.com/lists/oss-security/2020/10/13/3

Affected branches:

• master (28194fc4)
• 3.12-stable