(http://curl.haxx.se/docs/adv_20090303.html also known as CVE-2009-0037) in
  which previous libcurl versions (by design) can be tricked to access an
  arbitrary local/different file instead of a remote one when
  CURLOPT_FOLLOWLOCATION is enabled. This flaw is now fixed in this release
  together this the addition of two new setopt options for controlling this
  new behavior:

  o CURLOPT_REDIR_PROTOCOLS controls what protocols libcurl is allowed to
  follow to when CURLOPT_FOLLOWLOCATION is enabled. By default, this option
  excludes the FILE and SCP protocols and thus you nee to explicitly allow
  them in your app if you really want that behavior.

  o CURLOPT_PROTOCOLS controls what protocol(s) libcurl is allowed to fetch
  using the primary URL option. This is useful if you want to allow a user or
  other outsiders control what URL to pass to libcurl and yet not allow all
  protocols libcurl may have been built to support.

  CURLINFO_CONTENT_LENGTH_DOWNLOAD and CURLINFO_CONTENT_LENGTH_UPLOAD return
  -1 if the sizes aren't know. Previously these returned 0, make it impossible
  to detect the difference between actually zero and unknown.

  to the proper 'libcurl' as clearly this caused confusion.

  plain FTP connections, and it will then allow MKD to fail once and retry the
  CWD afterwards. This is especially useful if you're doing many simultanoes
  connections against the same server and they all have this option enabled,
  as then CWD may first fail but then another connection does MKD before this
  connection and thus MKD fails but trying CWD works! The numbers can
  (should?) now be set with the convenience enums now called
  CURLFTP_CREATE_DIR and CURLFTP_CREATE_DIR_RETRY.

  Tests has proven that if you're making an application that uploads a set of
  files to an ftp server, you will get a noticable gain in speed if you're
  using multiple connections and this option will be then be very useful.

  the condition in the previous request was unmet. This is typically a time
  condition set with CURLOPT_TIMECONDITION and was previously not possible to
  reliably figure out. From bug report #2565128
  (http://curl.haxx.se/bug/view.cgi?id=2565128)

to better know and track symbols in earlier libcurl versions

   getaddrinfo() sorts the response list

This isn't a libcurl bug since this is how getaddrinfo() is *supposed* to work!
Apparently you deal with this using the /etc/gai.conf file.

later)

  version 1.1 instead of 1.0 like before. This change also introduces the new
  proxy type for libcurl called 'CURLPROXY_HTTP_1_0' that then allows apps to
  switch (back) to CONNECT 1.0 requests. The curl tool also got a --proxy1.0
  option that works exactly like --proxy but sets CURLPROXY_HTTP_1_0.

  I updated all test cases cases that use CONNECT and I tried to do some using
  --proxy1.0 and some updated to do CONNECT 1.1 to get both versions run.

line and fixed a few typos.

  CURLOPT_SOCKS5_GSSAPI_SERVICE and CURLOPT_SOCKS5_GSSAPI_NEC to allow libcurl
  to do GSS-style authentication with SOCKS5 proxies. The curl tool got the
  options called --socks5-gssapi-service and --socks5-gssapi-nec to enable
  these.

  to set desired block size to use for TFTP transfers instead of the default
  512 bytes.

  They basically offer the same thing the NO_PROXY environment variable only
  offered previously: list a set of host names that shall not use the proxy
  even if one is specified.

  multi_socket interfaces. The work-around for apps is to simply remove the
  easy handle once the time is up. See also:
  http://curl.haxx.se/bug/view.cgi?id=2501457

new and non-standard one

corrupted in ouputs. Another report from Anthony Bryan.