HTTP authentication leak in redirects
Project curl Security Advisory, January 24th 2018 - Permalink
curl might leak authentication data to third parties.
When asked to send custom headers in its HTTP requests, curl will send that
set of headers first to the host in the initial URL but also, if asked to
follow redirects and a 30X HTTP response code is returned, to the host
mentioned in URL in the
Location: response header value.
Sending the same set of headers to subsequest hosts is in particular a problem
for applications that pass on custom
Authorization: headers, as this header
often contains privacy sensitive information or data that could allow others
to impersonate the curl-using client's request.
We are not aware of any exploit of this flaw.
This bug has existed since before curl 6.0. It existed in the first commit we have recorded in the project.
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2018-1000007 to this issue.
libcurl is used by many applications, but not always advertised as such.
In curl version 7.58.0, custom
Authorization: headers will be limited the
same way other such headers is controlled within curl: they will only be sent
to the host used in the original URL unless curl is told that it is ok to pass
on to others using the
NOTE: this solution creates a slight change in behavior. Users who actually want to pass on the header to other hosts now need to give curl that specific permission. You do this with --location-trusted with the curl command line tool.
A patch for CVE-2018-1000007 is available.
We suggest you take one of the following actions immediately, in order of preference:
A - Upgrade curl to version 7.58.0
B - Apply the patch to your version and rebuild
C - Do not enable CURLOPT_FOLLOWLOCATION if you pass on custom Authorization headers
It was reported to the curl project on January 18, 2018
We contacted distros@openwall on January 19.
curl 7.58.0 was released on January 24 2018, coordinated with the publication of this advisory.
Reported by Craig de Stigter. Patch by Daniel Stenberg.
Thanks a lot!