REDHAT-BUG-1000109: Medium severity OpenSSL libxml2 vulnerability

Published Aug 22, 2013
·
Updated

As reported on oss-security [1]:

So here are the CVE's for the two big ones, libxml2 and expat. Both are affected by the expansion of internal entities (which can be used to consume resources) and external entities (which can cause a denial of service against other services, be used to port scan, etc.).

To be clear:

==================== Internal entity expansion refers to the exponential/quadratic/fast linear expansion of XML entities, e.g.: ==================== <!DOCTYPE xmlbomb [ <!ENTITY a "1234567890" > <!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;"> <!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;"> <!ENTITY d "&c;&c;&c;&c;&c;&c;&c;&c;"> ]> <bomb>&d;</bomb>

or

<!DOCTYPE bomb [ <!ENTITY a "xxxxxxx... a couple of ten thousand chars"> ]> <bomb>&a;&a;&a;... repeat</bomb>

Which causes resources to be consumed

... Please use CVE-2013-0340 for expat internal entity expansion

[1] http://www.openwall.com/lists/oss-security/2013/02/22/4

Affected Software

2 affected components
OpenSSL libxml2
OpenSSL expat

Event History

Aug 22, 2013
Data Sourced
via Red Hat·05:30 PM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

What is the severity of REDHAT-BUG-1000109?

REDHAT-BUG-1000109 is a severe vulnerability that can lead to denial of service and potential resource exhaustion.

2

How do I fix REDHAT-BUG-1000109?

To fix REDHAT-BUG-1000109, ensure you update your libxml2 and Expat libraries to the latest patched versions provided by your vendor.

3

What are the affected versions related to REDHAT-BUG-1000109?

REDHAT-BUG-1000109 affects all versions of libxml2 and Expat that are susceptible to internal and external entity expansion vulnerabilities.

4

What types of attacks can REDHAT-BUG-1000109 facilitate?

REDHAT-BUG-1000109 can facilitate resource consumption attacks and denial of service attacks against affected services.

5

Is there a workaround for REDHAT-BUG-1000109?

While the best solution is to update the software, a temporary workaround is to configure your application to disable DTD processing.

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