[wp-trac] [WordPress Trac] #51891: Multiple xmlrpc attacks after last update

[WordPress Trac]

#51891: Multiple xmlrpc attacks after last update
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 Reporter:  attunist      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  General       |    Version:  5.5.3
 Severity:  major         |   Keywords:  needs-patch
  Focuses:                |
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 Hello,

 After the latest WP update, I have began noticing an increasing amount of
 xmlrpc attacks for exploits that reached new peaks some 20 hours ago and
 without signs of slowing down.

 With each attack I am getting the following entry in the error.log :

 PHP Warning:  call_user_func_array() expects parameter 1 to be a valid
 callback, array must have exactly two members in /home/.../public_html/wp-
 includes/class-wp-hook.php on line 289

 I have de-activated the majority of the plugins and specifically those
 updated during the last week but that didn't change the scenery.

 I am not a developer, I am a power WP user operating a multisite for a
 couple of years now and this is the first time I am noticing this
 aggressive hacking activity (hundreds of different IPs per hour just as to
 avoid immediate blacklisting). Also this is the first time I am opening a
 ticket in WP.org

 Thank you for your attention.

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Ticket URL: <https://core.trac.wordpress.org/ticket/51891>
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