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CVE-2015-8000: Responses with a malformed class attribute can trigger an assertion failure in db.c
Author: Michael McNally Reference Number: AA-01317 Views: 77548 Created: 2015-12-15 15:39 Last Updated: 2016-04-18 23:32 0 Rating/ Voters

Document Version:          
Posting date: 
15 December 2015
Program Impacted: 
Versions affected: 
9.0.x -> 9.9.8, 9.10.0 -> 9.10.3


An error in the parsing of incoming responses allows some records with an incorrect class to be accepted by BIND instead of being rejected as malformed.  This can trigger a REQUIRE assertion failure when those records are subsequently cached. Intentional exploitation of this condition is possible and could be used as a denial-of-service vector against servers performing recursive queries.


An attacker who can cause a server to request a record with a malformed class attribute can use this bug to trigger a REQUIRE assertion in db.c, causing named to exit and denying service to clients.  The risk to recursive servers is high. Authoritative servers are at limited risk if they perform authentication when making recursive queries to resolve addresses for servers listed in NS RRSETs.

CVSS Score:  7.1

CVSS Vector:  (AV:N/AC:M/Au:N/C:N/I:N/A:C)

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit:



Active exploits:

No known active exploits.

Solution:  Upgrade to the patched release most closely related to your current version of BIND. Public open-source branches can be downloaded from

  • BIND 9 version 9.9.8-P2
  • BIND 9 version 9.10.3-P2

BIND 9 Supported Preview edition is a feature preview version of BIND provided exclusively to ISC Support customers.

  • BIND 9 version 9.9.8-S3

Document Revision History:

1.0 Advance Notification, 24 November, 2015
1.1 Software releases 9.9.8-P1 and 9.10.3-P1 replaced with 9.9.8-P2 and 9.10.3-P2 to address CVE-2015-8461, advisory text and schedule updated, 8 December 2015
2.0 Public Disclosure, 15 December 2015
2.1 Edited to correct minor error in Description (repeated word), 15 December 2015

Related Documents:

See our BIND9 Security Vulnerability Matrix at for a complete listing of Security Vulnerabilities and versions affected.

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