• Bug 63652 has been marked as a duplicate of this bug. ***

This is also an active bug for Firefox users, tested on FF 28. Same steps to reproduce as above, same result (the corrected characters are added to both the word highlighted by the spellchecker, and the top of the document)

Note: the unwanted text can be removed with the "Undo" button. However, you can't "Undo" your spelling correction, undo goes grey after the first action)

Just a note that this is still happening: https://www.mediawiki.org/w/index.php?diff=prev&oldid=997038

It's still happening, several times a day on frwiki. If you need examples, there's an abuse filter set in place in frwiki that catches some of the problems

https://fr.wikipedia.org/w/index.php?title=Sp%C3%A9cial:Journal_du_filtre_antiabus&wpSearchFilter=216

Can't reproduce in FF or Chrome...

Might this be caused by ancient versions of Firefox/Chrome caused in part by some config of frwiki, or a bug in their dictionary app, or something?

This was happening in new versions of chrome as recently as a month ago, I can no longer reproduce.

According to a post on frwiki VE feedback page:

If you look at abuse filter 216, problem stopped to happen on June 19th, just after 1.24wmf9 being deployed, so probably a bug fixed in this release (in UTC+2 for Paris):
14h38 - 128.179.139.136
15h08 - 91.183.82.40
16h26 - 92.94.142.126 (not save)
19h00 - 195.101.137.28
19h22 - 195.101.137.28
20h35 - 87.90.125.24
20h35 - 90.32.27.10
21h12 - 41.189.42.250
23h07 - 1.24wmf9 on WP:fr [2]

[1] https://fr.wikipedia.org/w/index.php?title=Spécial:Journal_du_filtre_antiabus&wpSearchFilter=216
[2] https://wikitech.wikimedia.org/wiki/Server_admin_log

In that case, marking as FIXED in that release. Unsatisfying, but…