Bug 1053903 (CVE-2014-0015)

Daniel Stenberg reported the following vulnerability in cURL:

   libcurl can in some circumstances re-use the wrong connection when asked to
   do an NTLM-authenticated HTTP or HTTPS request.

   libcurl features a pool of recent connections so that subsequent requests
   can re-use an existing connection to avoid overhead.

   When re-using a connection a range of criterion must first be met. Due to a
   logical error in the code, a request that was issued by an application could
   wrongfully re-use an existing connection to the same server that was
   authenticated using different credentials. One underlying reason being that
   NTLM authenticates connections and not requests, contrary to how HTTP is
   designed to work and how other authentication methods work.

   An application that allows NTLM and another auth method (the bug only
   triggers if more than one auth method is asked for) to a server (that
   responds wanting NTLM) with user1:password1 and then does another operation
   to the same server with user2:password2 (when the previous connection was
   left alive) - the second request will re-use the same connection and since
   it'll then see that the NTLM negotiation is already made, it will just send
   the request over that connection thinking it uses 'user2' credentials when
   it is in fact still using the connection authenticated for user1...

   The set of auth methods to use is set with CURLOPT_HTTPAUTH.

   Two common auth defines in libcurl are CURLAUTH_ANY and CURLAUTH_ANYSAFE.
   Both of them ask for NTLM and other methods and can therefore trigger this
   problem.

   Applications can disable libcurl's re-use of connections and thus mitigate
   this problem, by using one of the following libcurl options to alter how
   connections are or aren't re-used: CURLOPT_FRESH_CONNECT,
   CURLOPT_MAXCONNECTS and CURLMOPT_MAX_HOST_CONNECTIONS (if using curl_multi
   API).

This will be corrected in upstream libcurl and curl 7.35.0.