Incorrect E-Mail validation #64

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1. tempico commented on Sep 11, 2017

   

   tempico

   on Sep 11, 2017

   Last edited by tempico

   Author

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   bypass PoC with flask

   @app.route('/email/', methods=['GET'])
   def page_email():
   	email = request.args["email"]
   	if validators.email(email):
   		return make_response(email, 200)
   

   
2. abentley commented on Feb 23, 2018

   

   abentley

   on Feb 23, 2018

   More actions

   So I think what's happening is that the $ is misplaced for domains. The part of the regex that deals with actual domains (rather than IP addresses) is r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+' r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?$)'

   The problem is that this permits arbitrary trailing characters, such as '>' after a valid domain, because it matches just the domain, not the invalid trailing characters.

   >>> re.match(r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+' r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?$)', 'example.org>', re.IGNORECASE).group(0)
   'example.org'
   

   Later, the code tests whether there was a match, not whether the input was matched perfectly.

   It appears that the intent was that the second part of the pattern would ensure termination, because it has a $. But the $ is part of a regex group that is not necessary to match 'example.org', so that group is ignored and 'example.org>' matches the regex just fine. Moving the $ after the second part of the pattern does solve this:

   >>> re.match(r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+' r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)$', 'example.org>', re.IGNORECASE).group(0)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   AttributeError: 'NoneType' object has no attribute 'group'
   >>> re.match(r'(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+' r'(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)$', 'example.org', re.IGNORECASE).group(0)
   'example.org'
   >>> 
   

   Checking whether match.group(0) == domain_part would also solve this, and might be more robust.
3. nandgator

   added

   bugIssue: Works not as designedIssue: Works not as designed

   on Mar 3, 2023
4. nandgator

   added 3 commits that reference this issue on Mar 3, 2023

   maint: improves `email` module

   ...

   This issue will close once commit 7264636 is merged into the 'master' branch.

   7264636

   maint: improves `email` module

   ...

   This issue will close once commit 6ae7a7f is merged into the 'master' branch.

   6ae7a7f

   maint: improves `email` module

   ...

   This issue will close once commit 0321a40 is merged into the 'master' branch.

   0321a40
5. nandgator

   closed this as completedin 0321a40on Mar 4, 2023
6. nandgator

   closed this as completedin #233on Mar 4, 2023