[SECURITY ADVISORY 4/4] libcurl not verifying certs for TLS to IP address / Winssl
Date: Wed, 26 Mar 2014 08:05:38 +0100 (CET)
libcurl not verifying certs for TLS to IP address / Winssl
Project cURL Security Advisory, March 26th 2014
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
This is a problem in libcurl built to use the SChannel/Winssl TLS backend.
SChannel/Winssl is the native library provided by Microsoft Windows.
Only users on Windows can be affected by this. And only if libcurl was built
to use the native TLS backend library.
The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2014-2522 to this issue.
2. AFFECTED VERSIONS
This flaw has existed ever since libcurl started to support the
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:
The fix was committed to the public source code repository because the full
security impact wasn't properly realized until after the fact.
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
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.
David Ryskalczyk made us aware of this flaw and wrote the patch.
Marc Hoersken helped coordinate the bug fix.
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