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Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')


Severity Medium
Score 6.1/10


Misskey is an open source, decentralized social media platform. In versions prior to 13.5.0 the link to the instance to the sender that appears when viewing a user or note received through ActivityPub is not properly validated, so by inserting a URL with a javascript scheme an attacker may execute JavaScript code in the context of the recipient. This issue has been fixed in version 13.5.0. Users are advised to upgrade. Users unable to upgrade should not "view on remote" for untrusted instances.

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CWE-79 - Cross Site Scripting

Cross-Site Scripting, commonly referred to as XSS, is the most dominant class of vulnerabilities. It allows an attacker to inject malicious code into a pregnable web application and victimize its users. The exploitation of such a weakness can cause severe issues such as account takeover, and sensitive data exfiltration. Because of the prevalence of XSS vulnerabilities and their high rate of exploitation, it has remained in the OWASP top 10 vulnerabilities for years.


Advisory Timeline

  • Published