Versions of the package markdown-to-jsx before 7.4.0 are vulnerable to Cross-site Scripting (XSS) via the src property due to improper input sanitization. An attacker can execute arbitrary code by injecting a malicious iframe element in the markdown.
https://security.snyk.io/vuln/SNYK-JS-MARKDOWNTOJSX-6258886
https://github.com/quantizor/markdown-to-jsx/commit/8eb74da825c0d8d2e9508d73c672bcae36ba555a