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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).