Subversion HTTP servers 1.5.0 to 1.6.16 (inclusive) are vulnerable
  to a remotely triggerable memory exhaustion DoS vulnerability.

Summary:
========

  Subversion's mod_dav_svn Apache HTTPD server module may in certain
  scenarios enter a logic loop which does not exit and which allocates
  memory in each iteration, ultimately exhausting all the available
  memory on the server.

  This can lead to a DoS.  There are no known instances of this
  problem being observed in the wild, but an exploit has been tested.

Known vulnerable:
=================

  Subversion HTTPD servers >= 1.5.0 and <= 1.6.16

Known fixed:
============

  Subversion 1.6.17
  svnserve (any version) is not vulnerable

Details:
========

  Subversion Apache/mod_dav_svn servers may be configured to provide
  path-based access control for files and directories stored in the
  Subversion repository.

  One such configuration -- identified by the use of the SVNPathAuthz
  httpd.conf directive with a value of "short_circuit" -- instructs
  mod_dav_svn to directly query the authorization logic in
  libsvn_repos to answer access questions ("Does the user who is
  requesting information from this server have permission to read
  SOME-PATH in SOME-REVISION?") rather than employing Apache
  subrequests to do the same.  With such a configuration in place,
  certain data sets and access rule combinations can trigger an
  infinite loop of logic that also allocates memory upon each
  iteration.  Over time, all available system memory will be allocated
  by the logic loop.

Severity:
=========

  A remote attacker may be able to deny access to a Subversion server
  by exhausting the available memory on the server.

Recommendations:
================

  We recommend all users to upgrade to Subversion 1.6.17.  Users of
  Subversion 1.5.x or 1.6.x who are unable to upgrade may apply the
  included patch.
  
  New Subversion packages can be found at:
  http://subversion.apache.org/packages.html

References:
===========

  CVE-2011-1783  (Subversion)

Reported by:
============

  Ivan Zhakov, VisualSVN