Mitigation for POST requests from malicious forms #1969
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In discussion on jupytergh-1830, I found that HTML forms in Firefox do not send an Origin header. You can therefore submit a POST request with an empty body to trigger certain actions, such as starting a kernel, avoiding the origin check we do. This mitigates that for creating files and starting kernels, by requiring a JSON body, even if there's no data. I cannot currently find a way to create a JSON body in a request sent from a form. The other cases I've found are interrupting and restarting kernels. This does not affect those cases, but they are only possible if you have a kernel ID.
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This doesn't feel like a proper fix, though, so I'd like to work out something better. Maybe we should block any requests without |
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Merged xsrf patch |
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In discussion on gh-1830, I found that HTML forms in Firefox do not send an Origin header. You can therefore submit a POST request with an empty body to trigger certain actions, such as starting a kernel, avoiding the origin check we do.
This mitigates that for creating files and starting kernels, by requiring a JSON body, even if there's no data. I cannot currently find a way to create a JSON body in a request sent from a form.
The other cases I've found are interrupting and restarting kernels. This does not affect those cases, but they are only possible if you have a kernel ID.