PowerDNS Security Advisory 2020-07: Cache pollution¶

• CVE: CVE-2020-25829

• Date: 13th of October 2020

• 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

• Severity: High

• Impact: Denial of service

• Exploit: This problem can be triggered by sending DNS queries

• Risk of system compromise: No

• Solution: Upgrade to a non-affected version

• Workaround: Filter ANY queries to prevent them from reaching the recursor.

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).