CB/CBSubs Captcha Code Mismatch Problem

Joomla! 3.7.2
CB 2.1.2
CBSubs 4.1.0
PHP 7.0.18

Following a user report of problems with the Captcha Code we use on our Step-by-Step CBSubs registration form, I tested it out and discovered that if the code is entered incorrectly (the error message for which appears after clicking the 'Sign Up' button on the fifth tab then returning and re-entering the displayed code, even if done correctly, always results in an error message and the user can go no further.

I subsequently discovered that if you return to re-enter an incorrectly entered Captcha Code and ask for audio 'Listen to Captcha' the value provided is completely different from that displayed e.g. screen displays 'rpwyjn' while the audio version is 'wcpqpn'. The audio version is always the same, no matter how many times you return to try to re-enter the displayed Captcha Code, but inputting this audio value instead still results in an error.

The only way round this problem is to refresh the Captcha Code to get a new value, after which the audio version matches correctly and the registration can be completed.

This disparity between the visual and audio values also occurs if the user starts the registration process and has to abandon it part-way through, then returns later. The first 'tab' they are shown is the last one they were in, the Captcha Code has changed and the error loop occurs.

So it's just the redisplayed captcha on failed captcha attempt that's incorrect? What captcha mode are you using? Could be a problem with it not generating a new code on every display. Please ensure you've the latest CB AntiSpam build installed. I was not able to confirm this on our demo site below.

demo.cbdemosites.com/community-builder/registration

Do you've caching of any kind enabled? If so try disabling it.

This disparity between the visual and audio values also occurs if the user starts the registration process and has to abandon it part-way through, then returns later. The first 'tab' they are shown is the last one they were in, the Captcha Code has changed and the error loop occurs.

The captcha code is tied to their session. If their session expires so will the captcha code. They'll need to refresh the captcha or you can increase session lifetime.

Thank you for your prompt reply.

Our registration process has five steps and is presented in Step-by-Step mode:
1. Subscription type (only one option at present)
2. Contact Details (including Captcha Code)
3. First Vehicle
4. Second Vehicle
5. Third Vehicle (ends with Sign Up button)

If the user completes all five steps but has incorrectly entered the Captcha Code then an error is displayed.

At this point the user has to use the 'Previous' buttons, to return to Step 2 to re-enter the code. This is when the disparity between the displayed and audio codes occurs; a new and different Captcha Code is displayed but the audio voices the previous code. At this point the user has no reason to refresh the Captcha Code, so gets an error when he reaches the end of the Registration process again, even if he has correctly entered the displayed value.

This is not a consistent error - occasionally a second or third try with the new and different Captcha Code allows the Registration process to complete, although the disparity between the visual and audio continues.

I have noticed that if the user tries to register with an already-registered email address and so has to return to Step 2 to enter a different one, then the same problem occurs - a new and different Captcha Code is displayed but the audio voices the previous code.

• The latest version of CB Antispam (cbantispam_3.0.1+2017.04.25) was installed several weeks ago.
• The Captcha mode is Code (internal)
• There is no caching enabled (Joomla! caching is OFF and I do not allow browser caching)
• The problem is not due to session expiry as I have been testing continually for several hours to try and get as much precise information as possible. I have also closed the browser completely during this testing period in case the problem lies with cookies that persist for the duration of the session.

Does the new captcha image displayed after an error work and it's just the audio that's wrong? By error you mean a PHP validation error where it sends them back to the registration form after submitting the form? It sounds like it's just the audio that's not properly outputting after a failed captcha attempt. I'm still unable to confirm this on our demo site below, are you?

demo.cbdemosites.com/community-builder/registration

After a Captcha error the audio is always wrong; sometimes the new captcha image displayed after an error works, sometimes it doesn't (but will then work on a third try).

I've attached a screen dump of the actual message, including the headings for the five steps in the registration process. When the Captcha error occurs I believe it is a PHP validation error as there is certainly a call to the server after submitting the form. The return is to Step 5 as shown, which is why the user has to return to Step 2 (Contact Info where the Captcha code is located) using the 'Previous' buttons.

Just in case you are wondering, I've never been able to get the Captcha to appear on Step 5 instead of Step 2. Perhaps if I could do that the problem would disappear.

I am also unable to reproduce the error on your demo page and I wonder if this is due to the demo being a single page registration, unlike our registration which runs over 5 steps.

I've retested every captcha mode and tested your issue several times with Code (Internal). I'm unable to reproduce your error. Reviewing the code the captcha will always generate a new code on display then cache it to session. It doesn't make sense for it to be able to access old captcha codes from just the audio. Are you sure there's no caching functionality enabled on your site?

I've never been able to get the Captcha to appear on Step 5 instead of Step 2. Perhaps if I could do that the problem would disappear.

As the captcha is just a field you should be able to move it to the last step assuming your last step allows fields. If the last step does allow fields and the captcha is not rendering on it then it sounds like you might have broken HTML or JS somewhere, which could be contributing to your issue.

I am also unable to reproduce the error on your demo page and I wonder if this is due to the demo being a single page registration, unlike our registration which runs over 5 steps.

Try disabling step by step on your site and see if issue persists or enabling on the demo site.

If issue persists after checking the above please PM backend super administrator login credentials and will take a look.