Headline
GHSA-mg3v-6m49-jhp3: WebOb's location header normalization during redirect leads to open redirect
Impact
When WebOb normalizes the HTTP Location header to include the request hostname, it does so by parsing the URL that the user is to be redirected to with Python’s urlparse, and joining it to the base URL. urlparse
however treats a //
at the start of a string as a URI without a scheme, and then treats the next part as the hostname. urljoin
will then use that hostname from the second part as the hostname replacing the original one from the request.
>>> parse.urlparse("//example.com/test/path")
ParseResult(scheme='', netloc='example.com', path='/test/path', params='', query='', fragment='')
WebOb uses urljoin
to take the request URI and joining the redirect location, so assuming the request URI is: https://example.org//example.com/some/path
, and the URL to redirect to (for example by adding a slash automatically) is //example.com/some/path/
that gets turned by urljoin
into:
>>> parse.urljoin("https://example.org//attacker.com/some/path", "//attacker.com/some/path/")
'https://attacker.com/some/path/'
Which redirects from example.org
where we want the user to stay to attacker.com
Patches
This issue is patched in WebOb 1.8.8
Older versions of WebOb continue to be vulnerable to this issue, and should be avoided.
Workarounds
Any use of the Response
class that includes a location
can be rewritten to make sure to always pass a full URI that includes the hostname to redirect the user to.
Thanks
- Sara Gao
This issue was reported via the Pylons Project Security List
Impact
When WebOb normalizes the HTTP Location header to include the request hostname, it does so by parsing the URL that the user is to be redirected to with Python’s urlparse, and joining it to the base URL. urlparse however treats a // at the start of a string as a URI without a scheme, and then treats the next part as the hostname. urljoin will then use that hostname from the second part as the hostname replacing the original one from the request.
>>> parse.urlparse("//example.com/test/path")
ParseResult(scheme='', netloc='example.com', path='/test/path', params='', query='', fragment='')
WebOb uses urljoin to take the request URI and joining the redirect location, so assuming the request URI is: https://example.org//example.com/some/path, and the URL to redirect to (for example by adding a slash automatically) is //example.com/some/path/ that gets turned by urljoin into:
>>> parse.urljoin("https://example.org//attacker.com/some/path", "//attacker.com/some/path/")
'https://attacker.com/some/path/'
Which redirects from example.org where we want the user to stay to attacker.com
Patches
This issue is patched in WebOb 1.8.8
Older versions of WebOb continue to be vulnerable to this issue, and should be avoided.
Workarounds
Any use of the Response class that includes a location can be rewritten to make sure to always pass a full URI that includes the hostname to redirect the user to.
Thanks
- Sara Gao
This issue was reported via the Pylons Project Security List
References
- GHSA-mg3v-6m49-jhp3
- Pylons/webob@f689bcf
Related news
Red Hat Security Advisory 2024-9989-03 - An update for python-webob is now available for Red Hat OpenStack Platform 17.1.
Red Hat Security Advisory 2024-9983-03 - An update for python-webob is now available for Red Hat OpenStack Platform 17.1.
Red Hat Security Advisory 2024-7941-03 - Red Hat OpenShift Container Platform release 4.13.52 is now available with updates to packages and images that fix several bugs and add enhancements. Issues addressed include an open redirection vulnerability.
Red Hat Security Advisory 2024-7590-03 - Red Hat OpenShift Container Platform release 4.12.67 is now available with updates to packages and images that fix several bugs and add enhancements. Issues addressed include code execution, open redirection, and out of bounds write vulnerabilities.
Red Hat Security Advisory 2024-6827-03 - Red Hat OpenShift Container Platform release 4.16.14 is now available with updates to packages and images that fix several bugs and add enhancements. Issues addressed include an open redirection vulnerability.
Ubuntu Security Notice 6984-1 - It was discovered that WebOb incorrectly handled certain URLs. An attacker could possibly use this issue to control a redirect or forward to another URL.