Some pages on this wiki are protected from being read with Lockdown. E.g. https://wiki.wikimedia.it/index.php?oldid=9999 shows a permission error however you can access the information at https://wiki.wikimedia.it/wiki/Pagina_principale?action=edit&undo=1202941&undoafter=9999. The temporary workaround here: https://www.mediawiki.org/wiki/2021-12_security_release/FAQ should be used until the wiki is upgraded (T268515).
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Even if T273607 suggests that secrets/password ~~are~~/were stored on the wiki, this is not considered an high problem anymore, since those legacy pages has been deleted since months.
Note that the risk is not high since this is not a corporate wiki with sensitive private information. The non-public information are //non-public// just for convenience, to keep internal discussions, stubs, and unnecessary-public-information away from being indexed and found by the general public (or something like that). Plus, members already can copy and share information with the public (the license encourages this - this probably doesn't happen because there's nothing interesting about it).