Fix XSS vulnerability in HTML utility functions #9
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sanitize beatmap metadata retrieved from db before formatting into html to prevent xss
yfxu
approved these changes
Dec 6, 2022
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Currently, the HTML utility functions defined in
utils/html_utils.pydo not perform any escaping/sanitization on the strings passed to them before formatting the strings into the HTML to be returned.Jinja does not sanitize the strings either as the HTML returned by this function is stored in JSON and eventually rendered in-browser using JavaScript.
This results in a stored cross site scripting (XSS) vulnerability wherein a malicious user may upload a beatmap whose metadata values contain HTML and JavaScript and then add it to their playlist on osulist.
This change will escape all occurrences of
<and>characters in the input string, preventing the delineation of any HTML tags within it.