Know every vulnerabilitybefore it knows you.
DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.
GHSA-mg3v-6m49-jhp3
No affected components available
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
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
Browse More
Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.
Checkout DevGuard