1903227 - Firefox autofill breaks forms from formsite.com (fills in hidden "subject_line")

Status: NEW

(Toolkit :: Form Autofill, defect, P3)

Description

[Calin Tanase (OOO until 22nd of Nov)]

Attachment: image.png

Report received via webcompat on github:

URL: https://caextreme.org/preregister/

Browser / Version: Firefox 127.0
Operating System: Linux
Tested Another Browser: Yes Chrome

Problem type: Something else
Description: Firefox autofill unexpectedly fills out subject_line with saved Street Address, breaking form
Steps to Reproduce:
If I allow autofill on this form, Firefox fills in my name and address (good!). But when I click [Next>>], form submission fails with "Please do not fill out the subject_line field.". The form does have a hidden subject_line field, and I confirm autofill immediately sets it to the street part of my saved address. Doesn't happen with chromium-browser's autofill.

I made a simpler test case on my web site https://www.skierpage.com/bugs/firefox_form_fill_in_bug.html

Note:

• Moved it here since is not a compatibility issue
• Feel free to move the issue if the Product/Component is wrong

Comment 1

[skierpage]

The form is in a frame and is implemented by Formsite. Their own "Contact us" form exhibits the same bug 😉. I suggested ways they could avoid the bug (don't have a hidden form field you don't use, move it below the address in the form). FWIW they recommend people not use form autofill; note the subject_line field has autocomplete="off". Maybe Firefox shouldn't autofill invisible fields or fields with autocomplete="off", and I'm not sure if the autofill component should fill in a field named "subject_line".