curl-7.50.3 (CVE-2016-7167)

[Douglas R. Reno]

New security-related/emergency security release

This one, being posted on the OSS Security release mailing list and meeting the Seamonkey Filter that I had setup, was *nice* enough to wake me up via a sound notification. I never hoped to actually have that feature work.

Bugfixes:

    CVE-2016-7167: escape and unescape integer overflows
    mk-ca-bundle.pl: use SHA256 instead of SHA1
    checksrc: detect strtok() use
    errors: new alias CURLE_WEIRD_SERVER_REPLY
    http2: support > 64bit sized uploads
    openssl: fix bad memory free (regression)
    CMake: hide private library symbols
    http: refuse to pass on response body with NO_NODY was set
    cmake: fix curl-config --static-libs
    mbedtls: switch off NTLM in build if md4 isn't available
    curl: --create-dirs on windows groks both forward and backward slashes 

Some useful links:

https://curl.haxx.se/changes.html#7_50_3
https://curl.haxx.se/docs/adv_20160914.html

I'd link to the openwall list email if I could get access to it - it just times out here.

Here's what triggered my alert:

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

The four libcurl functions `curl_escape()`, `curl_easy_escape()`,
`curl_unescape` and `curl_easy_unescape` perform string URL percent escaping
and unescaping. They accept custom string length inputs in signed integer
arguments. (The functions having names without "easy" being the deprecated
versions of the others.)

The provided string length arguments were not properly checked and due to
arithmetic in the functions, passing in the length 0xffffffff (2^32-1 or
`UINT_MAX` or even just -1) would end up causing an allocation of zero bytes
of heap memory that curl would attempt to write gigabytes of data into.

The use of 'int' for this input type in the API is of course unwise but has
remained so in order to maintain the API over the years.

We are not aware of any exploit of this flaw.

INFO
----

This flaw does not affect the curl command line tool.

The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2016-7167 to this issue.

AFFECTED VERSIONS
-----------------

This flaw exists in the following libcurl versions.

- Affected versions: libcurl 7.11.1 to and including 7.50.2
- Not affected versions: libcurl < 7.11.1 and libcurl >= 7.50.3

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


RECOMMENDATIONS
---------------

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

 A - Upgrade curl and libcurl to version 7.50.3

 B - Apply the patch to your version and rebuild

 C - Make sure you don't pass in string lengths larger than `INT_MAX`
     (typically 2^31) or negative values to the `curl_easy_(un)escape()`
     functions!

Originally reported as part of a PHP bug report.

I just built CURL before turning in for the night *earlier* - I'll do this.

[Douglas R. Reno]

Added CVE to the title (I might start doing that more often), and marked as high.

[Douglas R. Reno]

Fixed at r17759

[bdubbs@…]

Milestone renamed