Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Mutation XSS exists in Mark Text through 0.16.2 that leads to Remote Code Execution. NOTE: this might be considered a duplicate of CVE-2020-26870; however, it can also be considered an issue in the design of the "source code mode" feature, which parses HTML even though HTML support is not one of the primary advertised roles of the product.
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.