CVE-2012-5166: Specially crafted DNS data can cause a lockup in named

Solution Verified - Updated -


  • Red Hat Enterprise Linux (RHEL) 6
  • Red Hat Enterprise Linux (RHEL) 5
  • Red Hat Enterprise Linux (RHEL) 4
  • bind 9.x


  • Which versions of bind packages in Red Hat Enterprise Linux (RHEL) are affected by the CVE 2012-5166?
  • Is there a workaround?


According to ISC's KB the following versions are affected:

9.2.x -> 9.6.x, 9.4-ESV->9.4-ESV-R5-P1, 9.6-ESV->9.6-ESV-R7-P3, 9.7.0->9.7.6-P3, 9.8.0->9.8.3-P3, 9.9.0->9.9.1-P3

For Red Hat versions of BIND, the following errata have been released:

Please see the Red Hat Security CVE entry for more details:

  • What is a workaround for the CVE?
    According to advisory (ISC KB) section 'Workarounds:"
Setting the option 'minimal-responses' to 'yes' will prevent the lockup.

Accordigng to bind document:

**minimal-responses** If yes, then when generating responses the server will only add records to the au-
thority and additional data sections when they are required (e.g. delegations, negative responses).
This may improve the performance of the server. The default is no.

Root Cause

  • According to ISC KB:
If specific combinations of RDATA are loaded into a nameserver, either via cache or an authoritative zone, a subsequent query for a related record will cause named to lock up.

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