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URL request injection

Project curl Security Advisory, January 8th 2015 - Permalink

VULNERABILITY

When libcurl sends a request to a server via a HTTP proxy, it copies the entire URL into the request and sends if off.

If the given URL contains line feeds and carriage returns those will be sent along to the proxy too, which allows the program to for example send a separate HTTP request injected embedded in the URL.

Many programs allow some kind of external sources to set the URL or provide partial pieces for the URL to ask for, and if the URL as received from the user is not stripped good enough this flaw allows malicious users to do additional requests in a way that was not intended, or just to insert request headers into the request that the program didn't intend.

We are not aware of any exploit 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-2014-8150 to this issue.

AFFECTED VERSIONS

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

THE SOLUTION

libcurl 7.40.0 makes sure that the URL passed to the proxy may never contain neither carriage returns nor line feeds characters.

A patch for this problem is available at:

https://curl.haxx.se/CVE-2014-8150.patch

RECOMMENDATIONS

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

A - Upgrade to curl and libcurl 7.40.0

B - Apply the patch and rebuild libcurl

C - Only use URLs that are carefully stripped from line feeds and carriage returns

TIME LINE

It was first reported to the curl project on December 25 2014.

We contacted distros@openwall on December 28.

libcurl 7.40.0 was released on January 8th 2015, coordinated with the publication of this advisory.

CREDITS

Reported by Andrey Labunets (Facebook)

Thanks a lot!