Subversion: Vulnerability in mod_authz_svn

Background

Subversion is an advanced version control system, similar to CVS, which supports additional functionality such as the ability to move, copy and delete files and directories. A Subversion server may be run as an Apache module, a standalone server (svnserve), or on-demand over ssh (a la CVS’ “:ext:” protocol). The mod_authz_svn Apache module works with Subversion in Apache to limit access to parts of Subversion repositories based on policy set by the administrator.

Description

Users with write access to part of a Subversion repository may bypass read restrictions on any part of that repository. This can be done using an “svn copy” command to copy the portion of a repository the user wishes to read into an area where they have write access.

Since copies are versioned, any such copy attempts will be readily apparent.

Impact

This is a low-risk vulnerability. It affects only users of Subversion who are running servers inside Apache and using mod_authz_svn. Additionally, this vulnerability may be exploited only by users with write access to some portion of a repository.

Workaround

Keep sensitive content separated into different Subversion repositories, or disable the Apache Subversion server and use svnserve instead.

Resolution

All Subversion users should upgrade to the latest available version:

 # emerge sync
 
 # emerge -pv ">=dev-util/subversion-1.0.6"
 # emerve ">=dev-util/subversion-1.0.6"