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Date: Wed, 2 Nov 2016 08:12:49 +0100 (CET)
From: Daniel Stenberg <>
To: curl security announcements -- curl users <>,,
        libcurl hacking <>,
Subject: [SECURITY ADVISORY] curl invalid URL parsing with '#'

invalid URL parsing with '#'

Project cURL Security Advisory, November 2, 2016 -


curl doesn't parse the authority component of the URL correctly when the host
name part ends with a '#' character, and could instead be tricked into
connecting to a different host. This may have security implications if you for
example use a URL parser that follows the RFC to check for allowed domains
before using curl to request them.

Passing in `` would wrongly make curl send a
request to while your browser would connect to given the
same URL.

The problem exists for most protocol schemes.

We are not aware of any exploit of this flaw.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name
CVE-2016-8624 to this issue.


This flaw exists in the following curl versions.

- Affected versions: curl 7.1 to and including 7.50.3
- Not affected versions: curl >= 7.51.0

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


In version 7.51.0, the parser function is fixed.

A [patch for CVE-2016-8624]( is


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

  A - Upgrade curl and libcurl to version 7.51.0

  B - Apply the patch to your version and rebuild

  C - Strip out the parts of the URLs containing '#' before passing them to curl


It was first reported to the curl project on October 10 by Fernando Muñoz.

We contacted distros@...nwall on October 19.

curl 7.51.0 was released on November 2 2016, coordinated with the publication
of this advisory.


Thanks to Fernando Muñoz!



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