Captcha showing "wrong" picture

4 years 1 month ago #115925 by logicsurf

I've recently upgraded to the latest 141229-build and wanted to enable captcha on a survey. I have gd available in php and a picture gets created but it is a "wrong" picture:

I have the "Thumbnail Zoom Plus" plugin installed on Firefox which shows a bigger version of any picture if you hover with your mouse above the picture. When I start my survey and the captcha question shows, I see the picture e.g. as 2+95= but when I enter 97 I'm told this is the wrong answer. When I hover with my mouse over the 2+95= image I suddenly see a zoomed up image which says: 3+40= and if I give the answer to that zoomed up image, it is accepted.

How can this be? I first thought it is a caching problem of my server but it is not that I am seeing "old" images because I have never used catcha before and there have been no repeated questions.

I'm slightly confused. Any ideas?

Is there any way to replace limesurvey's own captcha with an external one to work around this issue?

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4 years 1 month ago #115931 by c_schmitz
THe problem is caused by your plugin. It loads the image a 2nd time which causes a new captcha to be generated.

Best regards

Carsten Schmitz
LimeSurvey project leader

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