Bug #87917

Bot manipulated form fields lead to exception

Added by Harald Holzmann 11 months ago. Updated about 1 month ago.

Should have
Target version:
Start date:
Due date:
% Done:


TYPO3 Version:
PHP Version:
Is Regression:
Sprint Focus:



I found out that if you manipulate the hidden fields of a form, typo3 raises an error. Error message is "Uncaught TYPO3 Exception: #1320830276: A hashed string must contain at least 40 characters, the given string was only 6 characters long. | TYPO3\CMS\Extbase\Security\Exception\InvalidArgumentForHashGenerationException thrown in file ......../htdocs/typo3_src-8.7.24/typo3/sysext/extbase/Classes/Security/Cryptography/HashService.php in line 90" or "Uncaught TYPO3 Exception: #1320830018: The given string was not appended with a valid HMAC. TYPO3\CMS\Extbase\Security\Exception\InvalidHashException thrown in file| ......./htdocs/typo3_src-8.7.24/typo3/sysext/extbase/Classes/Security/Cryptography/HashService.php in line 94".

If a bot or user manipulates for example the hidden trustedproperties field "name="tx_vayoga_contact[__trustedProperties]" or "name="tx_vayoga_contact[__referrer][@request]".

In my opinion the exception should be checked before. For example if the string is long enough or can be hmac parsed. But to be honest it spams the protocol. You cannot focus on the real issues.

What you think about it?

Kind regards,

Related issues

Related to TYPO3 Core - Feature #90134: Send 404 - BAD REQUEST on invalid hmacs from extbase forms New 2020-01-16


#1 Updated by Georg Ringer 11 months ago

  • Description updated (diff)

#2 Updated by Georg Ringer 10 months ago

  • Status changed from New to Rejected

Thanks for creating the issue. We don't see this is problem as the exception is correct, the request must fail if the hmac is wrong.

If you have too many issues like that, try to block the bot in your firewall, waf or htaccess.

#3 Updated by Daxboeck no-lastname-given 7 months ago

  • Target version set to next-patchlevel
  • TYPO3 Version changed from 8 to 9

Dear Georg Ringer,

I strongly disagree !

It is annoying to have the error log flooded with HMAC "errors".
Any URL sent by external sources must never result in "errors" at all because this is no system and no internal plugin error.
The purpose of "errors" in the log is to detect bugs in the system itself and to be able to fix them.
It cannot be the purpose to have something in the error log, which you cannot avoid by fixing extensions.

If you think that all these HMAC errors should be reported somewhere, then they belong to a separate log file which preferably could be read by tools like "denyhosts" and then can be used to automatically block the source.

The current solution which floods the log of larger TYPO3 systems like ours is simply idiotic.

Best regards,


#4 Updated by Christian Eßl about 1 month ago

I think that throwing an exception in this case (that is logged) isn't the best solution.

What do you think about returning a status code 400 - BAD REQUEST in this case?

#5 Updated by Christian Eßl 8 days ago

  • Related to Feature #90134: Send 404 - BAD REQUEST on invalid hmacs from extbase forms added

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