Libxml2 2.9.3 fails to parse multi-byte character in large CDATA section that is split across buffer

[Loïc Dardant]

Ubuntu 16.04 packages libxml2 version 2.9.3*, which contains a regression documented here: https://git.gnome.org/browse/libxml2/commit/?id=4f8606c13cb7f2684839f850b83de5ce647d3ca7

Full release notes of 2.9.4 can be seen here: http://xmlsoft.org/news.html

The bug will affect XML push parser that fails with bogus UTF-8 encoding error when multi-byte character in large CDATA section is split across buffer, which can be quite common.

As Xenial is an LTS version and this bug is quite *critical*, I wonder if we should provide an update to fix this one. If I remember correctly, we're not supposed to update to a newer version a given package for a given version of Ubuntu, but as this version of Ubuntu will be used in many servers in the coming years and XML parsing is quite a common task, it may help a lot of developers to have a backported fix of this issue.

Let me know you if you need more information.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Joern Heissler (joernheissler)]

I'm currently moving servers to 16.04. I'm affected by this bug.
Would you please fix it in 16.04? Cheers!

[Launchpad Janitor (janitor)]

This bug was fixed in the package libxml2 - 2.9.3+dfsg1-1ubuntu0.2

---------------
libxml2 (2.9.3+dfsg1-1ubuntu0.2) xenial-security; urgency=medium

  * SECURITY UPDATE: format string vulnerabilities
    - debian/patches/CVE-2016-4448-1.patch: fix format string warnings in
      HTMLparser.c, SAX2.c, catalog.c, configure.ac, debugXML.c,
      encoding.c, entities.c, error.c, include/libxml/parserInternals.h,
      include/libxml/xmlerror.h, include/libxml/xmlstring.h, libxml.h,
      parser.c, parserInternals.c, relaxng.c, schematron.c, testModule.c,
      valid.c, xinclude.c, xmlIO.c, xmllint.c, xmlreader.c, xmlschemas.c,
      xmlstring.c, xmlwriter.c, xpath.c, xpointer.c.
    - debian/patches/CVE-2016-4448-2.patch: fix format string warnings in
      libxml.h, relaxng.c, xmlschemas.c, xmlstring.c.
    - debian/libxml2.symbols: added new symbol.
    - CVE-2016-4448
  * SECURITY UPDATE: use-after-free via namespace nodes in XPointer ranges
    - debian/patches/CVE-2016-4658.patch: disallow namespace nodes in
      XPointer ranges in xpointer.c.
    - CVE-2016-4658
  * SECURITY UPDATE: use-after-free in XPointer range-to function
    - debian/patches/CVE-2016-5131-1.patch: fix XPointer paths beginning
      with range-to in xpath.c, xpointer.c.
    - debian/patches/CVE-2016-5131-2.patch: fix comparison with root node
      in xmlXPathCmpNodes in xpath.c.
    - CVE-2016-5131
  * debian/patches/lp1652325.patch: XML push parser fails with bogus
    UTF-8 encoding error when multi-byte character in large CDATA section
    is split across buffer (LP: #1652325)

 -- Marc Deslauriers <email address hidden> Tue, 14 Mar 2017 16:06:13 -0400

[Benjamin Bolton (benpbolton)]

Confirming libxml2:amd64 (2.9.3+dfsg1-1ubuntu0.2) fixes the issue. Appreciate the release!