[wp-trac] [WordPress Trac] #33626: wp_favicon_request() may set a bad value for Content-Length header

[WordPress Trac]

#33626: wp_favicon_request() may set a bad value for Content-Length header
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 Reporter:  martiusweb    |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  General       |    Version:  3.0
 Severity:  normal        |   Keywords:
  Focuses:                |
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 wp_favicon_request() catches /favicon.ico requests early and sends an
 empty response, avoiding the core to be loaded.

 The current implementation sets the header Content-Length to 0 then exits.
 However, the ob_cache will be flushed and may sent data (for instance, a
 BOM - Byte Order Mark left in wp-config.php).

 With Apache 2.2 and probably several other common servers implementations
 (including nginx), it lead to a bad response, since the client should not
 expect a body but will receive the 3 bytes of the BOM. Some proxies might
 get confused.

 This can be fixed by calling ob_clean() or ob_end_clean() in
 wp_favicon_request().

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Ticket URL: <https://core.trac.wordpress.org/ticket/33626>
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