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PowerDNS Security Advisory 2019-03: Insufficient validation in the HTTP remote backend

  • CVE: CVE-2019-3871
  • Date: March 18th 2019
  • Affects: PowerDNS Authoritative up to and including 4.1.6
  • Not affected: 4.1.7, 4.0.7
  • Severity: High
  • Impact: Denial of Service, Information Disclosure, Content spoofing
  • Exploit: This problem can be triggered via crafted queries
  • Risk of system compromise: No
  • Solution: Upgrade to a non-affected version

An issue has been found in PowerDNS Authoritative Server when the HTTP remote backend is used in RESTful mode (without post=1 set), allowing a remote user to cause the HTTP backend to connect to an attacker-specified host instead of the configured one, via a crafted DNS query. This can be used to cause a denial of service by preventing the remote backend from getting a response, content spoofing if the attacker can time its own query so that subsequent queries will use an attacker-controlled HTTP server instead of the configured one, and possibly information disclosure if the Authoritative Server has access to internal servers.

This issue has been assigned CVE-2019-3871.

PowerDNS Authoritative up to and including 4.1.6 is affected. Please note that at the time of writing, PowerDNS Authoritative 3.4 and below are no longer supported, as described in

We would like to thank Adam Dobrawy, Frederico Silva and Gregory Brzeski from for finding and subsequently reporting this issue!