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"Content-Type" header code execution

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We are looking to find a fix for the code execution bug found in May of 2021:

Mozilla Firefox is vulnerable to code execution by a remote attacker who can convince a user to open a malicious file. By manipulating the "Content-Type" header of a file the attacker can cause Firefox to execute scripts concealed in files that appear to be of non-executable types.

We are looking to find a fix for the code execution bug found in May of 2021: Mozilla Firefox is vulnerable to code execution by a remote attacker who can convince a user to open a malicious file. By manipulating the "Content-Type" header of a file the attacker can cause Firefox to execute scripts concealed in files that appear to be of non-executable types.

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If you use my test document you will see that Firefox 96 still works the same way: when the server indicates this combination:

Content-Type: text/html Content-Disposition: attachment; filename=test.jpg

Firefox corrects the file name during the save process from test.jpg to test.jpg.html and you can open it as an HTML page rather than a corrupt JPEG image.

I don't know whether anyone has filed a bug. Normally security researchers would have done that before making a public disclosure but it is hard to search for security bugs.

If you want to file a new bug:

https://bugzilla.mozilla.org/

Les dette svaret i sammenhengen 👍 0

All Replies (5)

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Can you link to information about that vulnerability? To prevent a delay in your post appearing, add a space before the .com or .org in your link. (Otherwise, the reply is sent to the link spam moderation queue.)

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I think this is what they're doing:

https://www.jeffersonscher.com/res/test_jpg.php

Adding screenshot of download dialog:

Endret av jscher2000 - Support Volunteer

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That was the site I saw about this issue but no official notice or fix which is what is needed.

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Valgt løsning

If you use my test document you will see that Firefox 96 still works the same way: when the server indicates this combination:

Content-Type: text/html Content-Disposition: attachment; filename=test.jpg

Firefox corrects the file name during the save process from test.jpg to test.jpg.html and you can open it as an HTML page rather than a corrupt JPEG image.

I don't know whether anyone has filed a bug. Normally security researchers would have done that before making a public disclosure but it is hard to search for security bugs.

If you want to file a new bug:

https://bugzilla.mozilla.org/