[SECURITY ADVISORY 1/4] libcurl wrong re-use of connections
Date: Wed, 26 Mar 2014 08:04:30 +0100 (CET)
libcurl wrong re-use of connections
Project cURL Security Advisory, March 26th 2014
libcurl can in some circumstances re-use the wrong connection when asked to
do transfers using other protocols than HTTP and FTP.
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 an
error in the code, a transfer that was initiated by an application could
wrongfully re-use an existing connection to the same server that was
authenticated using different credentials. The existing logic basically only
worked well enough for HTTP and FTP, while all other network protocols were
silently, but erroneously, assumed to work like HTTP. Basically, protocols
that use connection oriented authentication need a new connection when new
credentials are used.
Affected protocols include: SCP, SFTP, POP3(S), IMAP(S), SMTP(S) and
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
(This problem is very similar to a problem previously reported to NTLM HTTP
connections, named CVE-2014-0015)
The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2014-0138 to this issue.
2. AFFECTED VERSIONS
This flaw has existed ever since libcurl started to support these other
protocols, although the code has been restructured a few times over the
years so the mistake has altered shape.
Affected versions: from libcurl 7.10.6 to and including 7.35.0
Not affected versions: libcurl before 7.10.6 and >= 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 connections are re-used more strictly.
A patch for this problem is available at:
We suggest you take one of the following actions immediately, in order of
A - Upgrade to curl and libcurl 7.36.0
B - Apply the patch and rebuild libcurl
5. TIME LINE
It was reported to the curl project on February 15th 2014. We contacted
distros_at_openwall on March 16 2014.
libcurl 7.36.0 was released on March 26th 2014, coordinated with the
publication of this advisory.
Bug reported and patch written by Steve Holme.
Thanks a lot!
-- / daniel.haxx.se ------------------------------------------------------------------- List admin: http://cool.haxx.se/list/listinfo/curl-library Etiquette: http://curl.haxx.se/mail/etiquette.htmlReceived on 2014-03-26