When a custom Safelist permits certain raw-text elements, jsoup may incorrectly sanitize malformed HTML containing a tag name that ends in a control character. The tag may acquire the parsing behavior of a different element, causing content that should remain text to be emitted as active markup after serialization and potentially allowing XSS.

jsoup’s built-in Safelists are unaffected.

Upgrade to jsoup 1.23.1.

Until upgrading, do not permit raw-text elements in custom Safelists used to clean untrusted HTML.

This fix addresses malformed tag-name handling only.

Permitting raw-text elements in a custom Safelist does not make their contents inherently safe. For example, applications that permit style must apply appropriate CSS safeguards separately, because jsoup does not parse or sanitize CSS.