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AUSCERT External Security Bulletin Redistribution
CVE-2013-2494: A Vulnerability in libdns Could Cause
Excessive Memory Use in ISC DHCP 4.2
2 April 2013
AusCERT Security Bulletin Summary
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2013-2494
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CVE-2013-2494: A Vulnerability in libdns Could Cause Excessive Memory Use in
ISC DHCP 4.2
A memory exhaustion bug has been discovered in libdns, which is used by ISC
DHCP 4.2. Theoretically this could be exploited to cause memory exhaustion in
ISC DHCP 4.2.
Document Version: 2.0
Posting date: 26 March 2013
Program Impacted: ISC DHCP
Versions affected: 4.2.0 -> 4.2.5. ISC DHCP versions prior to 4.2.0
(including 4.1-ESV) are not affected.
Exploitable: From adjacent networks
Exploitation of a memory exhaustion bug in libdns is theoretically possible in
ISC DHCP 4.2, which uses the library from BIND 9 for Dynamic DNS.
Unlike vulnerabilities which can be exercised by a machine impersonating a
malicious client, exploitation of this vulnerability is complex and requires
either controlling a nameserver with whom the DHCP server process is
communicating or successfully spoofing traffic to appear as such. These
preconditions result in a CVSS severity of "Low", but operators using
vulnerable versions of DHCP 4.2 are nevertheless recommended to upgrade to
DHCP 4.2.5-P1, which prevents exploitation of the libdns library defect.
Servers which are targeted by a successful attack will exhaust all memory
available to the server process, which is likely to crash the DHCP server and
may affect other processes running on the same physical machine when system
memory is exhausted.
CVSS Score: 4.9
CVSS Equation: (AV:N/AC:H/Au:S/C:N/I:N/A:C)
For more information on the Common Vulnerability Scoring System and to obtain
your specific environmental score please visit:
None. (Or do we want to mention that you can change the build process for
the BIND libraries?)
No known active exploits.
Solution: Upgrade to DHCP 4.2.5-P1
Document Revision History:
1.0 Phase One - Advance Notification, 18 March 2013
1.2 Phase Two & Three Notification, 25 March 2013
2.0 Public notification, 26 March 2013
Japanese Translation: [planned]
Spanish Translation: [planned]
German Translation: [planned]
Portugese Translation: [planned]
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Note: ISC patches only currently supported versions. When possible we indicate
EOL versions affected.
ISC Security Vulnerability Disclosure Policy: Details of our current security
advisory policy and practice can be found here:
This Knowledge Base article https://kb.isc.org/article/AA-00880 is the complete
and official security advisory document.
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Â© 2001-2013 Internet Systems Consortium
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