Docsify Cross-site Scripting

docsify 4.12.1 is affected by Cross Site Scripting (XSS) because the search component does not appropriately encode Code Blocks and mishandles the " character. (2021-04-02, CVE-2021-30074)

This affects the package docsify before 4.12.0. It is possible to bypass the remediation done by CVE-2020-7680 and execute malicious JavaScript through the following methods 1) When parsing HTML from remote URLs, the HTML code on the main page is sanitized, but this sanitization is not taking place in the sidebar. 2) The isURL external check can be bypassed by inserting more “////” characters (2021-02-19, CVE-2021-23342)

docsify prior to 4.11.4 is susceptible to Cross-site Scripting (XSS). Docsify.js uses fragment identifiers (parameters after # sign) to load resources from server-side .md files. Due to lack of validation here, it is possible to provide external URLs after the /#/ (domain.com/#//attacker.com) and render arbitrary JavaScript/HTML inside docsify page. (2020-07-20, CVE-2020-7680)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>