Description
Versions of the package github.com/yuin/goldmark/renderer/html before 1.7.17 are vulnerable to Cross-site Scripting (XSS) due to improper ordering of URL validation and normalization. The renderer validates link destinations using a prefix-based check (IsDangerousURL) before resolving HTML entities. This allows an attacker to bypass protocol filtering by encoding dangerous schemes using HTML5 named character references. For example, a payload such as javascript:alert(1) is not recognized as dangerous during validation, leading to arbitrary script execution in the context of applications that render the URL.
Problem types
Credits
Catalin Iovita (Snyk Security Research)
References
security.snyk.io/...THUBCOMYUINGOLDMARKRENDERERHTML-15838406
github.com/...ommit/cb46bbc4eca29d55aa9721e04ad207c23ccc44f9