libcurl not verifying certs for TLS to IP address / Darwinssl
         =============================================================

Project cURL Security Advisory, March 26th 2014
http://curl.haxx.se/docs/security.html

1. VULNERABILITY

   When asked to do a TLS connection (HTTPS, FTPS, IMAPS, etc) to a URL
   specified with an IP address instead of a name, libcurl would wrongly not
   verify the server's name in the certificate. The signature (whether it was
   signed by a trusted CA) and validity (whether the date was within the
   certificate's lifetime and it was not revoked) verifications were still
   performed.

   This is a problem in libcurl built to use the SecureTransport/Darwinssl
   backend. SecureTransport/Darwinssl is the TLS library present and used on
   Mac OS X and iOS.

   Only users on Mac OS X or iOS can be affected by this. And only if libcurl
   was built to use the native TLS backend library.

   This problem was initially used as an example of the Apple SSL bug that hit
   the news in late February 2014[1] but that was not correct.

   The Common Vulnerabilities and Exposures (CVE) project has assigned the name
   CVE-2014-1263 to this issue.

2. AFFECTED VERSIONS

   This flaw has existed ever since libcurl started to support the
   SecureTransport/Darwinssl backend.

   Affected versions: from libcurl 7.27.0 to and including 7.35.0
   Not affected versions: libcurl >= 7.36.0

   libcurl is used by many applications, but not always advertised as such!

3. THE SOLUTION

   libcurl 7.36.0 makes sure that all TLS using requests verify the host name
   even if specified as an IP address in the URL.

   A patch for this problem is available at:

     https://github.com/bagder/curl/commit/afc6e5004fabee

   The fix was committed to the public source code repository because the full
   security impact wasn't properly realized until after the fact.

4. RECOMMENDATIONS

   We suggest you take one of the following actions immediately, in order of
   preference:

   A - Upgrade to curl and libcurl 7.36.0

   B - Apply the patch and rebuild libcurl

   C - Rebuild libcurl to use another TLS backend

5. TIME LINE

   It was discovered by the curl project during late February 2014.

   libcurl 7.36.0 was released on March 26th 2014, coordinated with the
   publication of this advisory.

6. CREDITS

   This was indirectly reported by numerous people and it was also clarified by
   Adam Langley that it wasn't the problem Apple themselves fixed. Roland Moriz
   is credited in Apple's security note[2].

   David Ryskalczyk wrote the patch.

   Nick Zitzmann helped coordinate the bug fix.

   Apple claims to have fixed this problem in an update of their own. That was
   done independently from and without informing the curl project.

   [1] = https://www.imperialviolet.org/2014/02/22/applebug.html
   [2] = http://support.apple.com/kb/HT6150

   Thanks a lot!

-- 
  / daniel.haxx.se
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