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PowerDNS Security Advisory 2015-03: Packet parsing bug can lead to crashes

  • CVE: CVE-2015-5311
  • Date: November 9th 2015
  • Credit: Chris Hofstaedtler of Deduktiva GmbH
  • Affects: PowerDNS Authoritative Server 3.4.4 through 3.4.6
  • Not affected: PowerDNS Authoritative Server 3.3.x and 3.4.7 and up
  • Severity: High
  • Impact: Degraded service or Denial of service
  • Exploit: This problem can be triggered by sending specially crafted query packets
  • Risk of system compromise: No
  • Solution: Upgrade to a non-affected version
  • Workaround: run the process inside the guardian or inside a supervisor

A bug was found using afl-fuzz in our packet parsing code. This bug, when exploited, causes an assertion error and consequent termination of the the pdns_server process, causing a Denial of Service.

When the PowerDNS Authoritative Server is run inside the guardian (--guardian), or inside a supervisor like supervisord or systemd, it will be automatically restarted, limiting the impact to a somewhat degraded service.

PowerDNS Authoritative Server 3.4.4 - 3.4.6 are affected. No other versions are affected. The PowerDNS Recursor is not affected.

PowerDNS Authoritative Server 3.4.7 contains a fix to this issue. A minimal patch is available here.

This issue is unrelated to the issues in our previous two Security Announcements (2015-01 and 2015-02).

We’d like to thank Chris Hofstaedtler of Deduktiva GmbH for finding and reporting this issue.