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XSS in blog post #719

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Nhoya opened this Issue Jan 3, 2018 · 2 comments

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Nhoya commented Jan 3, 2018

You can trigger an XSS creating a markdown note with the following payload:

<IMG SRC=/ onerror="String.fromCharCode(88,83,83)"></img>

Converting it to a blogpost and opening the link will trigger the XSS

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kurtseifried Jan 25, 2018

Is this supposed to be blocked? In general if you can edit the page the expectation is that you can insert whatever you want. so unless this is supposed to be explicitly blocked (docs around this?) it would be seen as a hardening issue and not a security vulnerability from the CVE perspective.

kurtseifried commented Jan 25, 2018

Is this supposed to be blocked? In general if you can edit the page the expectation is that you can insert whatever you want. so unless this is supposed to be explicitly blocked (docs around this?) it would be seen as a hardening issue and not a security vulnerability from the CVE perspective.

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Nhoya Jan 25, 2018

You can't directly edit the blog post. You can write a note that has filter to prevent XSS(without result since i already reported multiple XSS in markdown notes) that can be converted in blog post. There is a sanitize function to prevent a simple <script>alert(1)</script> from printing the alert when converted in blogpost, but this payload you can bypass it.

Having a feedback about it from the developers would be nice

Nhoya commented Jan 25, 2018

You can't directly edit the blog post. You can write a note that has filter to prevent XSS(without result since i already reported multiple XSS in markdown notes) that can be converted in blog post. There is a sanitize function to prevent a simple <script>alert(1)</script> from printing the alert when converted in blogpost, but this payload you can bypass it.

Having a feedback about it from the developers would be nice

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