Vulnerability Note VU#559980

ISC Bind 9 IXFR or DDNS update combined with high query rate DoS vulnerability

Original Release date: 22 Feb 2011 | Last revised: 23 Feb 2011


A denial-of-service condition exists in certain cases when an ISC Bind server processes a IXFR transfer or dynamic update.


The ISC security advisory states:

"When an authoritative server processes a successful IXFR transfer or a dynamic update, there is a small window of time during which the IXFR/update coupled with a query may cause a deadlock to occur. This deadlock will cause the server to stop processing all requests. A high query rate and/or a high update rate will increase the probability of this condition."


An attacker may cause the Bind server to stop processing all requests.


BIND 9.7.1 or 9.7.2 users should upgrade to BIND 9.7.3. Earlier versions are not vulnerable. BIND 9.5 is End of Life and is not supported by ISC. BIND 9.8 is not vulnerable.

The ISC advisory contains the following workaround:
"Depending on your performance requirements, a work-around may be available. ISC was not able to reproduce this defect in 9.7.2 using -n 1, which causes named to use only one worker thread, thus avoiding the deadlock. If your server is powerful enough to serve your data with a single processor, this option may be fast to implement until you have time to perform an upgrade."

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
Internet Systems ConsortiumAffected24 Jan 201123 Feb 2011
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



Thanks to ISC for reporting this vulnerability.

This document was written by Jared Allar.

Other Information

  • CVE IDs: CVE-2011-0414
  • Date Public: 22 Feb 2011
  • Date First Published: 22 Feb 2011
  • Date Last Updated: 23 Feb 2011
  • Severity Metric: 4.50
  • Document Revision: 12


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