Security Advisory for Bugzilla 2.18.5, 2.20.2, 2.22, and 2.23.2

Max Kanat-Alexander mkanat at
Sun Oct 15 10:01:25 UTC 2006


Bugzilla is a Web-based bug-tracking system, used by a large number of
software projects.

This advisory covers six security issues that have recently been 
fixed in the Bugzilla code:

+ Sometimes the information put into the <h1> and <h2> tags in Bugzilla
  was not properly escaped, leading to a possible XSS vulnerability.

+ Bugzilla administrators were allowed to put raw, unfiltered HTML into
  many fields in Bugzilla, leading to a possible XSS vulnerability. 
  Now, the HTML allowed in those fields is limited.

+ attachment.cgi could leak the names of private attachments

+ The "deadline" field was visible in the XML format of a bug, even to
  users who were not a member of the "timetrackinggroup."

+ A malicious user could pass a URL to an admin, and make the admin
  delete or change something that he had not intended to delete or 

+ It is possible to inject arbitrary HTML into the showdependencygraph.cgi
  page, allowing for a cross-site scripting attack.

We strongly advise that 2.18.x users upgrade to 2.18.6. 2.20.x users
should upgrade to 2.20.3. 2.22 users, and users of 2.16.x or below,
should upgrade to 2.22.1.

Development snapshots of 2.23 before 2.23.3 are also vulnerable to all
of these issues. If you are using a development snapshot, you should
upgrade to 2.23.3, use CVS to update, or apply the patches from the 
specific bugs listed below.

Vulnerability Details

Issue 1
Class:       Cross-Site Scripting
Versions:    2.15 and above
Description: Bugzilla sometimes displays admin-provided data in page 
             headers (meaning the <h1> and <h2> HTML tags of a page).
             Sometimes, this data was not properly escaped, leading to 
             the possibility of a Cross-Site Scripting vulnerability.
             For the most part, this was only exploitable by 
             administrators, and so is not of critical severity.

Issue 2
Class:       Cross-Site Scripting
Versions:    2.0 and above
Description: Bugzilla allows administrators to put HTML in the
             descriptions of products, components, and other items. It
             also allows HTML in certain other fields. Before the
             most recent releases of Bugzilla, this HTML was completely
             unfiltered. These fields are only editable by
             certain users, who are specified by the admin. This makes
             this vulnerability less severe. However, these users could
             use this exploit to perform Cross-Site Scripting attacks
             on nearly all users of a particular Bugzilla (including
             users with higher permission levels than themselves).

             Bugzilla now allows only certain HTML tags in those fields,
             protecting users from a Cross-Site Scripting attack.

Issue 3
Class:       Information Leak
Versions:    2.17 and above
Description: When viewing an attachment in "Diff" mode, a user who is
             not in the "insidergroup" (the group required to view
             private attachments) can read the one-line descriptions
             of all attachments, even "private" attachments.

Issue 4
Class:       Information Leak
Versions:    2.19.2 and above
Description: Bugzilla has a "deadline" field, which is usually only
             visible to people in the "timetrackinggroup" group.
             However, it was exposed in the XML format of a bug to all

Issue 5
Class:       Security Enhancement
Versions:    2.0 and above
Description: Bugzilla updates, deletes, and creates data through a
             web interface. Administrators update things like user
             accounts through this interface. All of these pages accept
             URL variables in both GET and POST formats.

             A malicious user could craft a URL that would edit a user
             (or any other admin-protected item), and then using a
             service like TinyURL, could obscure the URL so that an
             administrator couldn't tell what it was. Then, getting the
             administrator to click on that URL, the action would be
             performed, against the administrator's will.

             This is now prevented. Bugzilla will only accept changes
             on administrative pages if they come from Bugzilla's own
             forms. That is, you have to use the form to make changes--
             you now cannot just click a URL and accidentally make an
             administrative change to Bugzilla.

             Although technically this affects all versions of Bugzilla,
             it has only been fixed on our most recent release (2.22.1
             and our latest development snapshot, 2.23.3), because the
             fix was too invasive to backport further. Administrators
             of previous versions of Bugzilla should only click on URLs
             from users that they fully trust.

Issue 6
Class:       Cross-Site Scripting
Versions:    2.15 and above
Description: showdependencygraph.cgi is a script that allows you to display
             a graph of how bugs are related. There is a cross-site
             scripting vulnerability in this script that allows for arbitrary
             HTML injection. The user would have to follow a malicious URL
             in order to trigger the attack--it is not possible for another
             user to otherwise inject HTML into the page for the current

Vulnerability Solutions

The fixes for all of the security bugs mentioned in this advisory
are included in the 2.18.6, 2.20.3, 2.22.1, and 2.23.3 releases. 
Upgrading to these releases will protect installations from possible
exploits of these issues.

Full release downloads, patches to upgrade Bugzilla from previous
versions, and CVS upgrade instructions are available at:

Specific patches for each of the individual issues can be found on the
corresponding bug reports for each issue, at the URL given in the
reference for that issue in the list above.


The Bugzilla team wish to thank the following people for their
assistance in locating, advising us of, and assisting us to fix
these situations:

Frédéric Buclin*
Dave Miller
Gervase Markham
Gavin Shelley
Max Kanat-Alexander
Myk Melez
Josh "timeless" Soref
Olav Vitters
Adam Merrifield

* The Bugzilla Project would like to express special thanks to 
  Frédéric. He worked many, many volunteer hours to fix many of the
  issues above, and is largely responsible for most of these issues
  being fixed. They would not have been fixed without him.

General information about the Bugzilla bug-tracking system can be found

Comments and follow-ups can be directed to the
newsgroup or the support-bugzilla mailing list. has directions for accessing these 

-Max Kanat-Alexander
Release Manager, Bugzilla Project

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