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Blocking JavaScript does not work in local html files (file://...) if the character encoding is not specified. #267

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achvo opened this issue Jun 10, 2020 · 1 comment
Open
9 tasks done

Blocking JavaScript does not work in local html files (file://...) if the character encoding is not specified. #267

achvo opened this issue Jun 10, 2020 · 1 comment
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@achvo
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achvo commented Jun 10, 2020

Prerequisites

  • I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • This is not a support issue or a question
    • Support issues and questions are handled at /r/uMatrix
  • I tried to reproduce the issue when...
    • uMatrix is the only extension
    • uMatrix with default lists/settings
    • using a new, unmodified browser profile
  • I am running the latest version of uMatrix
  • I checked the documentation to understand that the issue I report is not a normal behavior
  • I used the logger to rule out that the issue is caused by my ruleset

Description

Blocking JavaScript does not work in local html files (file://...) if the character encoding is not specified.
This bug does not occur if the character encoding is specified.

A specific URL where the issue occurs

See Steps to Reproduce.

Steps to Reproduce

  1. Block JavaScript in uMatrix completely. Rule: * * script block
  2. Create the following local html file: 
    <!DOCTYPE html>
<html lang="en">
    <head>
        <!-- Do not specify character encoding <meta charset="UTF-8"> -->
        <title>Test</title>
    </head>
    <body>
        <h1>Is JavaScript being executed?</h1>
        <h1 id='answer'>No, it is not.</h1>
        <script>document.getElementById('answer').innerText = 'Yes, it is.'</script>
    </body>
</html>
  3. Open the local html file in Firefox (file://pathToFile/test.html).
  4. Reload page (F5).
  5. Blocking does not work and JavaScript is being executed.

Ruleset

Default + * * script block

Supporting evidence

supporting_evidence

Your environment

  • uMatrix version: 1.4.0
  • Browser Name and version: Firefox 77.0.1
  • Operating System and version: Ubuntu 18.04 LTS
@gorhill
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gorhill commented Jun 10, 2020

I can reproduce.

It's not even about the character encoding, just having an empty meta tag causes the CSP directive to take effect. This looks like a Firefox issue to me, whether the CSP directive takes effect or not should not depend on the existence of another meta tag.

@uBlock-user uBlock-user added the something to address something to address label Jun 10, 2020
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@gorhill @uBlock-user @achvo