[oss-security] CVE request: PowerDNS in default configuration is vulnerable to DoS attack

It was found 1 that in default configuration PowerDNS is allowed to
consume more file descriptors than is available for a default installation
of many Linux distributions.
Default configuration is: 2 threads / 2048 max-mthreads, which leads
to a theoretical FD consumption of 4096. Default FD limit on many
distributions is 1024.
This can potentially lead to the DoS attack.

Workaround (from 1):

• Reduce max-mthreads to 512 (or threads to 1 and max-mthreads to
  1024) (max-mthreads was introduced in Recursor 3.2; but if you are
  running a version that old, please upgrade it!)
• Run ‘ulimit -n 32768? before starting (perhaps put this in
  /etc/init.d/ script). There’s little reason to skip on this number.
• Investigate defaults in /etc/security/limits.conf

Patch is available at 2

References:

https://bugs.mageia.org/show_bug.cgi?id=13521
https://bugzilla.redhat.com/show_bug.cgi?id=1109231

Can a CVE please be assigned if one has not been already?

Thanks.
– Vasyl Kaigorodov | Red Hat Product Security Team PGP: 0xABB6E828 A7E0 87FF 5AB5 48EB 47D0 2868 217B F9FC ABB6 E828