Brad Hill of iSEC Partners discovered that many XML implementations are vulnerable to external entity expansion issues, which can be used for various purposes such as firewall circumvention, disguising an IP address, and denial-of-service. libxml2 was susceptible to these problems when performing string substitution during entity expansion.

For the stable distribution (squeeze), these problems have been fixed in version 2.7.8.dfsg-2+squeeze7. For the testing (wheezy) and unstable (sid) distributions, these problems have been fixed in version 2.8.0+dfsg1-7+nmu1. We recommend that you upgrade your libxml2 packages.

XML is a metalanguage to let you design your own markup language. A regular markup language defines a way to describe information in a certain class of documents (eg HTML). XML lets you define your own customized markup languages for many classes of document. It can do this because it's written in SGML, the international standard metalanguage for markup languages.

libxml2 on Debian Linux

This check tests the installed software version using the apt package manager.

• http://www.debian.org/security/2013/dsa-2652.html

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Updated on 2015-03-25