oss-security - CVE for Ruby Entity expansion DoS vulnerability in REXML (XML bomb)

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Date: Wed, 06 Mar 2013 11:25:13 -0700
From: Kurt Seifried <kseifried@...hat.com>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>,
        Mitre CVE assign department <cve-assign@...re.org>,
        Steven Christey <coley@...re.org>,
        Ruby Security Team <security@...y-lang.org>
Subject: CVE for Ruby Entity expansion DoS vulnerability in REXML (XML bomb)

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Hash: SHA1

http://www.ruby-lang.org/en/news/2013/02/22/rexml-dos-2013-02-22/

=====

Unrestricted entity expansion can lead to a DoS vulnerability in
REXML. (The CVE identifier will be assigned later.) We strongly
recommend to upgrade ruby.
Details

When reading text nodes from an XML document, the REXML parser can be
coerced in to allocating extremely large string objects which can
consume all of the memory on a machine, causing a denial of service.

Impacted code will look something like this:

document = REXML::Document.new some_xml_doc
document.root.text

When the `text` method is called, entities will be expanded. An
attacker can send a relatively small XML document that, when the
entities are resolved, will consume extreme amounts of memory on the
target system.

Note that this attack is similar to, but different from the Billion
Laughs attack. This is also related to CVE-2013-1664 of Python.

All users running an affected release should either upgrade or use one
of the work arounds immediately.

=====

Please use CVE-2013-1821 for this issue. I apologize in advance if a
CVE was requested through other channels but we need a CVE for this
ASAP. Also for future reference you can get CVEs via

http://people.redhat.com/kseifrie/CVE-OpenSource-Request-HOWTO.html

- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993

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