CVE-2006-4095: Multiple DoS vulnerabilities


Certain query sequences can cause server failure

Posting date: 
06 Sep 2006
Program Impacted: 
Versions affected: 
9.2, 9.3.0-9.2, pre-release versions of 9.4.0


SIG Query Processing:

Recursive servers:

  • Queries for SIG records will trigger a assertion failure if more than one SIG (covered) RRset is returned.
  • Exposure can be minimized by restricting sources that can ask for recursion.

Authoritative servers:

  • If a nameserver is serving a RFC 2535 DNSSEC zone and is queried for the SIG records where the are multiple SIG(covered) RRsets (e.g. a zone apex) then named will trigger a assertion failure when it trys to construct the response.

Excessive Recursive Queries INSIST failure:

It is possible to trigger a INSIST failure by sending enough recursive queries that the response to the query arrives after all the clients looking for the response have left the recursion queue. Exposure can be minimized by restricting sources that canask for recursion. Note for BIND 9.2.x: Code handling this path for 9.2.x has been determined to be wrong, though ISC has not been able to detect an execution path that would trigger the erroneous code in 9.2.x. Nonetheless a patch is provided.



Active exploits:

None known at this time


Upgrade to BIND 9.4.0b2, BIND 9.3.3rc2, BIND 9.3.2-P1, BIND 9.2.7rc1 or BIND 9.2.6-P1 (or later).

See also CVE-2006-4096

Acknowledgements: ISC would like to thank The Measurement Factory for bringing this to our attention.

Related Documents:

See our BIND Security Matrix for a complete listing of Security Vulnerabilities and versions affected. 

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