libcurl SASL buffer overflow vulnerability
                   ==========================================

Project cURL Security Advisory, February 6th 2013
http://curl.haxx.se/docs/security.html

1. VULNERABILITY

   libcurl is vulnerable to a buffer overflow vulnerability when communicating
   with one of the protocols POP3, SMTP or IMAP.

   When negotiating SASL DIGEST-MD5 authentication, the function
   Curl_sasl_create_digest_md5_message() uses the data provided from the server
   without doing the proper length checks and that data is then appended to a
   local fixed-size buffer on the stack.

   This vulnerability can be exploited by someone who is in control of a server
   that a libcurl based program is accessing with POP3, SMTP or IMAP. For
   applications that accept user provided URLs, it is also thinkable that a
   malicious user would feed an application with a URL to a server hosting code
   targetting this flaw.

   This vulnerability can be used for remote code execution (RCE) on vulnerable
   systems.

   Both curl the command line tool and applications using the libcurl library
   are vulnerable.

   There is no known exploit for this problem. There has been

   The Common Vulnerabilities and Exposures (CVE) project has assigned the name
   CVE-2013-0249 to this issue.

2. AFFECTED VERSIONS

   Affected versions: curl 7.26.0 to and including 7.28.1
   Not affected versions: curl < 7.26.0 and >= 7.29.0

   Also note that libcurl is used by many applications, and not always
   advertised as such.

3. THE SOLUTION

   libcurl 7.29.0 implements proper bounds checking and will not overflow any
   buffers even if unrealisticly long data chunks are received.

4. RECOMMENDATIONS

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

   A - Upgrade to curl and libcurl 7.29.0

   B - Apply this patch and rebuild libcurl

       http://curl.haxx.se/curl-sasl.patch

   C - Rebuild curl with support for vulnerable protocols IMAP, POP3 and SMTP
       disabled.

   D - Disable the vulnerable protocols IMAP, POP3 and SMTP at run-time to
       forbid libcurl from using them. You can do this with the
       CURLOPT_PROTOCOLS option.

5. TIME LINE

   Vulnerability found and patched by Volema (http://volema.com/).

   It was reported to the curl project on January 30th 2013.

   curl 7.29.0 was released on February 6th 2013, coordinated with the
   publication of this flaw.

6. CREDITS

   Reported and fixed by Volema. Thanks a lot!

-- 
  / daniel.haxx.se
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