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Date: Wed, 12 Feb 2014 00:20:30 +1100
From: Murray McAllister <>
Subject: CVE-2013-6401 Jansson hash collision issue

As reported to the distros mailing list:

Hi all,

Florian Weimer of the Red Hat Product Security Team found that the
hashing implementation in Jansson, a library for encoding, decoding and
manipulating JSON data, was susceptible to predictable hash collisions.
A remote attacker could use this flaw to cause an application using
Jansson to use an excessive amount of CPU time by sending a crafted JSON
document containing a large number of parameters whose names map to the
same hash value. (CVE-2013-6401)

With regards to affected versions, I am guessing only 2.4-2 and 2.4-3
were checked (by Red Hat).

Many thanks to Florian Weimer and Petri Lehtinen (upstream) for their
extensive work on the patch:

(Feel free to copy the above CVE-2013-6401 description paragraph in any
of your bugs or advisories.)

Red Hat bug: (to be
opened shortly)


Murray McAllister / Red Hat Security Response Team

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