CVE-2015-8373 - ISC Kea: unexpected termination while handling a malformed packet

ISC Kea may terminate unexpectedly (crash) while handling a malformed client packet.

CVE: CVE-2015-8373

Document version: 2.0

Posting date: 22 December 2015

Program impacted: ISC Kea

Versions affected: 0.9.2, 1.0.0-beta

Severity: Critical

Exploitable: Remotely

Description:

Related defects in the kea-dhcp4 and kea-dhcp6 servers can cause the server to crash during option processing if a client sends a malformed packet.

• The kea-dhcp4 server is vulnerable only in versions 0.9.2 and 1.0.0-beta, and furthermore only when logging at debug level 40 or higher. Servers running kea-dhcp4 versions 0.9.1 or lower, and servers which are not logging or are logging at debug level 39 or below, are not vulnerable.
• The kea-dhcp6 server is vulnerable only in versions 0.9.2 and 1.0.0-beta, and furthermore only when logging at debug level 45 or higher. Servers running kea-dhcp6 versions 0.9.1 or lower, and servers which are not logging or are logging at debug level 44 or below, are not vulnerable.

Impact:

An attacker sending a crafted malformed packet can cause an ISC Kea server providing DHCP services to IPv4 or IPv6 clients to exit unexpectedly.

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: http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:M/Au:N/C:N/I:N/A:C).

Workarounds:

For DHCPv4 services, disabling debug logging or logging at debug levels of 39 or lower will protect ISC Kea against this vulnerability.

For DHCPv6 services, disabling debug logging or logging at debug levels of 44 or lower will protect ISC Kea against this vulnerability.

Active exploits: No known active exploits exist; this vulnerability was found during internal testing.

Solution: Upgrade to the patched release most closely related to your current version of ISC Kea. These can all be downloaded from https://www.isc.org/downloads.

• ISC Kea version 0.9.2-P1
• ISC Kea version 1.0.0-beta2

Document revision history:

1.0 Advance Notification, 15 December 2015
1.1 Revised, 18 December 2015 (limiting vulnerable versions to 0.9.2 and 1.0.0-beta)
1.2 Revised, 21 December 2015 (DHCPv4 workarounds determined and added)
2.0 Public Disclosure, 22 December 2015

Related documents:

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