XSS vulnerability in NCrypt

[Framartin]

For transparency reason (and with the authorization of the NCrypt maintainer), the email I sent to NCrypt the 02/03/2017 is reproduced below:

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I just found an XSS vulnerability in NCrypt.

How to reproduce

• A malicious user create a paste with the content: <script>alert('XSS')</script>
• (S)he sends the link to the targeted user
• The targeted user clones the paste
• The JS payload is executed

As far as I tested it, the choice of programming language don't change the result.

Note: the payload can be "hidden" in a lot of text or code in order to "trick" users.

As far as I know, the impact is quite limited because you don't store the previous posted links in the browser, but it can be used to de-anonymize users for example.

I found this vulnerability because I'm currently and voluntarily searching for XSS vulnerabilities in a lot of FLOSS.

I remain available for any additional comments or questions.

Best,
Martin

[luggs-co]

Fixed.