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Bug 491366 (CVE-2013-4563) - Kernel : "udp6_ufo_fragment()" Denial of Service Vulnerability (CVE-2013-4563)
Summary: Kernel : "udp6_ufo_fragment()" Denial of Service Vulnerability (CVE-2013-4563)
Alias: CVE-2013-4563
Product: Gentoo Security
Classification: Unclassified
Component: Kernel (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Kernel Security
Depends on:
Reported: 2013-11-15 20:09 UTC by Agostino Sarubbo
Modified: 2022-03-25 15:44 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---


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Description Agostino Sarubbo gentoo-dev 2013-11-15 20:09:04 UTC
From ${URL} :


Saran Neti has reported a vulnerability in Linux Kernel, which can be exploited by malicious people 
to cause a DoS (Denial of Service).

The vulnerability is caused due to an error within the "udp6_ufo_fragment()" function 
(net/ipv6/udp_offload.c) and can be exploited to cause a kernel panic via specially crafted UDP 

Successful exploitation requires the kernel to be built with the IPv6 protocol (CONFIG_IPV6) 
support and an Ethernet driver (e.g. virtio-net) with the UDP Fragmentation Offload (UFO) feature 
enabled using TBF qdisc.

The vulnerability is reported in versions 3.10.19 and 3.11.8.

Fixed in the source code repository.

Further details available to Secunia VIM customers

Provided and/or discovered by:
Saran Neti, TELUS Security Labs via the linux-netdev mailing list.

Original Advisory:
Saran Neti:
Comment 1 GLSAMaker/CVETool Bot gentoo-dev 2013-11-27 21:46:00 UTC
CVE-2013-4563 (
  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.
Comment 2 John Helmert III archtester Gentoo Infrastructure gentoo-dev Security 2022-03-25 15:44:29 UTC
Fix in 3.12.4 onwards