CVE-2013-4563: Canonical Ubuntu Linux

High severity, CVSS 7.1. EPSS: 3.9% chance of exploitation in the next 30 days.

The udp6_ufo_fragment function in net/ipv6/udp_offload.c in the Linux kernel through 3.12, when UDP Fragmentation Offload (UFO) is enabled, does not properly perform a certain size comparison before inserting a fragment header, which allows remote attackers to cause a denial of service (panic) via a large IPv6 UDP packet, as demonstrated by use of the Token Bucket Filter (TBF) queueing discipline.

Affected products

• Canonical Ubuntu Linux: version 12.04 only; version 13.10 only
• Linux Linux Kernel: from 3.9.8, up to and including 3.10.23; from 3.11, before 3.12.4 (fixed in 3.12.4)

Published 2013-11-20. Last modified 2026-06-16.