cookie parser out of boundary memory access
===========================================

Project cURL Security Advisory, April 22nd 2015 -
[Permalink](http://curl.haxx.se/docs/adv_20150422C.html)

VULNERABILITY
-------------

libcurl supports HTTP "cookies" as documented in RFC 6265. Together with each
individual cookie there are several different properties, but for this
vulnerability we focus on the associated "path" element. It tells information
about for which path on a given host the cookies is valid.

The internal libcurl function called `sanitize_cookie_path()` that cleans up
the path element as given to it from a remote site or when read from a file,
did not properly validate the input. If given a path that consisted of a
single double-quote, libcurl would index a newly allocated memory area with
index -1 and assign a zero to it, thus destroying heap memory it wasn't
supposed to.

At best, this gets unnoticed but can also lead to a crash or worse. We have
not researched further what kind of malicious actions that potentially this
could be used for.

Applications have to explicitly enable cookie parsing in libcurl for this
problem to trigger, and if not enabled libcurl will not hit this problem.

We are not aware of any exploits of this flaw.

INFO

----
This flaw can also affect the curl command line tool if a similar operation
series is made with that.
The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2015-3145 to this issue.
AFFECTED VERSIONS
-----------------
- Affected versions: from libcurl 7.31.0 to and including 7.41.0
- Not affected versions: libcurl >= 7.42.0
libcurl is used by many applications, but not always advertised as such!
THE SOLUTION
------------
libcurl 7.42.0 better verifies the input string.
A patch for this problem is available at [URL will be updated]:
     http://curl.haxx.se/CVE-2015-3145.patch
RECOMMENDATIONS
---------------
We suggest you take one of the following actions immediately, in order of
preference:
A - Upgrade to curl and libcurl 7.42.0
B - Apply the patch and rebuild libcurl
C - Avoid using cookies with libcurl
TIME LINE
---------
It was first reported to the curl project on April 16 2015. We contacted
distros_at_openwall on April 17th.
libcurl 7.42.0 was released on April 22nd 2015, coordinated with the
publication of this advisory.
CREDITS
-------
Reported by Hanno Böck
Thanks a lot!
-- 
  / daniel.haxx.se

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Received on 2015-04-22