Exactly, what the hell. Apart from Google Chrome (and Firefox, which isn't in the list below) I don't even have any of these other browsers installed!

  $ fd claude_browser_extension.json ~/Library
  /Users/miguno/Library/Application Support/BraveSoftware/Brave-Browser/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/Vivaldi/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/Arc/User Data/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/Microsoft Edge/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/com.operasoftware.Opera/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/Chromium/NativeMessagingHosts/com.anthropic.claude_browser_extension.json
  /Users/miguno/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_browser_extension.json

I also checked Claude Desktop > Settings > Extensions. Not a single word or mention of these aforementioned extensions for browsers. I have zero Claude Desktop extensions installed and, without reading the article, would have never guessed that these extensions for browsers were installed.

Claude Desktop repeatedly installed/updated these 7 extensions since the beginning of February on my Apple machine. Every entry in the filtered log below is for all 7 extensions:

    $ grep "Installed native host manifest" ~/Library/Logs/Claude/main.log | sed -e 's/ at \/Users\/.*//' | awk '{ print $1" "$2 }' | sort -n | uniq
    2026-02-04 18:53:21
    2026-02-04 23:33:26
    2026-02-04 23:34:20
    2026-02-04 23:34:27
    2026-03-16 09:29:18
    2026-03-17 11:52:22
    2026-03-18 22:22:22
    2026-03-19 14:49:34
    2026-03-20 09:42:03
    2026-03-20 10:10:39
    2026-04-02 22:50:26
    2026-04-02 22:57:56
    2026-04-10 19:38:38
    2026-04-10 19:40:51
    2026-04-12 18:52:36
    2026-04-12 19:10:04
    2026-04-12 20:07:21
    2026-04-15 12:19:46
    2026-04-15 12:20:16
    2026-04-15 12:29:45
    2026-04-16 22:15:47
    2026-04-16 22:24:19
    2026-04-18 10:58:13
    2026-04-18 15:06:54