Sourced from sanitize-html's changelog.

2.17.6 (2026-07-10)

Fixes

• Allow transformTags to emit text when textFilter is set, even if the tag is initially empty. This is consistent with the documentation. Thanks to spokodev for the fix.

Security

• Fixed an XSS/allowlist bypass in which the contents of a raw-text element (textarea or xmp) nested inside an svg or math root were re-emitted without HTML-escaping. sanitize-html treated that content as inert raw text because htmlparser2 10.x classified raw-text elements by tag name and ignored the namespace, but a real HTML5 parser treats textarea/xmp as ordinary foreign elements inside SVG/MathML and re-parses their contents as live markup. As a result, markup and event-handler attributes that the allowlist never permitted (for example <svg><textarea><img src=x onerror=alert(1)>) could survive sanitization and execute in the browser. This is now fixed on two fronts: htmlparser2 was upgraded to 12.x, which is namespace-aware and parses textarea/xmp inside SVG/MathML as ordinary elements, so their non-allowlisted children (such as the injected img) are dropped by the allowlist instead of being preserved as raw text; and any raw-text content sanitize-html still emits for these tags (at HTML integration points such as foreignObject/mtext, or outside foreign content) is always HTML-escaped. The default configuration is not affected; the precondition is an allowedTags that includes svg or math together with textarea or xmp. Thanks to khoadb175 for responsibly disclosing the vulnerability.
• Fixed a mutation-XSS / allowedTags bypass affecting configurations that allow the textarea or xmp raw-text tags. htmlparser2 10.x did not recognize an end tag with a trailing solidus (e.g. </textarea/>) as closing the element, so it kept the following markup as raw text, but a spec-compliant browser treats </textarea/> as a valid close and parses that markup as a live element. Because raw-text content was re-emitted without escaping, a payload such as <textarea></textarea/><img src=x onerror=...> could smuggle non-allowlisted, executable markup through the sanitizer. The default configuration was not affected. This is now defended at two layers: htmlparser2 was upgraded to 12.x, whose tokenizer closes these end tags correctly, and the raw text sanitize-html emits for these tags is always escaped so no < can reopen a tag when the output is re-parsed (textarea, an RCDATA element whose entities htmlparser2 decodes, is escaped like normal text, while xmp, a raw-text element, has only its angle brackets escaped to avoid double-encoding already-encoded entities). Because htmlparser2 is ESM-only from version 11 onward, sanitize-html now requires Node.js >=22.12.0 (the first 22.x release in which require() of an ES module is available unflagged). Thanks to bibu123456 for reporting the vulnerability and Kayiz-PT for coordinating the disclosure (GHSA-jxwj-j7wr-gfrw).

2.17.5 (2026-06-10)

Security

• Added a number of new attributes to be protected against unsafe URLs, e.g. javascript: and similar. None of these are used in the default configuration of sanitize-html or apostrophe or likely to be used there, and some attributes, like an action for a form, are inherently unsafe to allow if XSS protection is your goal. Nevertheless it makes sense to block certain URL types where they are not appropriate. Some attributes are not supported at all by modern browsers but are included for completeness. Thanks to crattack for reporting the vulnerability.
• Address a potential vulnerability when nonTextTags is configured in a nonstandard way. While it is never a good idea to remove known non-text tags from the standard list e.g. script, styles, etc., this change ensures that doing so does not result in nested tags being passed through without sanitization when they are not expressly allowed. (ApostropheCMS would never trigger this situation.) Thanks to Dipanshu singh for pointing out the issue and contributing the fix.

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