CVE-2016-8624
invalid URL parsing with '#'
Project curl Security Advisory, November 2, 2016 - Permalink
VULNERABILITY
curl does not parse the authority component of the URL correctly when
the host name part ends with a hash (#) 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 http://example.com#@evil.com/x.txt would
wrongly make curl send a request to evil.com while your browser would
connect to example.com given the same URL.
The problem exists for most protocol schemes.
INFO
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2016-8624 to this issue.
CWE-172: Encoding Error
Severity: Medium
AFFECTED VERSIONS
This flaw exists in the following curl versions.
- Affected versions: curl 6.0 to and including 7.50.3
- Not affected versions: curl < 6.0 and curl >= 7.51.0
- Introduced-in: https://github.com/curl/curl/commit/ae1912cb0d494b48d5
libcurl is used by many applications, but not always advertised as such!
SOLUTION
In version 7.51.0, the parser function is fixed.
As a side-effect of this fix, using the # character as
part of the user or password fields in the URL is no longer supported.
According to RFC
3986 section 2.3 it is not allowed. See issue #1216
RECOMMENDATIONS
We suggest you take one of the following actions immediately, in order of preference:
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
TIMELINE
It was first reported to the curl project on October 10.
We contacted distros@openwall on October 19.
curl 7.51.0 was released on November 2 2016, coordinated with the publication of this advisory.
CREDITS
- Reported-by: Fernando Muñoz
- Patched-by: Daniel Stenberg
Thanks a lot!