[Bug 1602608] Re: mailman crash for subscription in webinterface

Mark Sapiro mark at msapiro.net
Thu Jul 14 18:01:49 EDT 2016

Actually, the problem is both simpler and more wide spread than you
report. The underlying issue is the Content-Type: text/plain header sent
with the POST request. It doesn't matter what if anything the data is.
'language' is a red herring. It only appears in the tracebacks from the
subscribe CGI because that is what's being requested in the subscribe
CGI's first call to the getvalue method of the cgi.FieldStorage

The way the Python cgi module works, the FieldStorage instance has
different properties depending on the Content-Type: header in the POST.
If the content type is application/x-www-form-urlencoded as would be the
case in a normal POST from a browser the FieldStorage instance is a
dictionary-like mapping of key, value pairs that can be retrieved via
the getvalue method. If the content type is text/plain, the FieldStorage
instance just has a string value and the getvalue method throws

This actually affects every one of Mailman's CGIs, not just subscribe,
and without knowing how the error was triggered, I probably wouldn't
have determined the cause.

In the spirit of not throwing uncaught exceptions, even when people, web
crawlers, etc. unwittingly or maliciously craft defective requests, I
have committed http://bazaar.launchpad.net/~mailman-
coders/mailman/2.1/revision/1663 to return an error document with a 400
status for such requests.

** Changed in: mailman
   Importance: Undecided => Low

** Changed in: mailman
       Status: Incomplete => Fix Committed

** Changed in: mailman
    Milestone: None => 2.1.23

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