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.
Patches
Upgrade to jsoup 1.23.1.
Workarounds
Until upgrading, do not permit raw-text elements in custom Safelists used to clean untrusted HTML.
Additional security considerations
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.
References
When a custom
Safelistpermits 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.
Patches
Upgrade to jsoup 1.23.1.
Workarounds
Until upgrading, do not permit raw-text elements in custom Safelists used to clean untrusted HTML.
Additional security considerations
This fix addresses malformed tag-name handling only.
Permitting raw-text elements in a custom
Safelistdoes not make their contents inherently safe. For example, applications that permitstylemust apply appropriate CSS safeguards separately, because jsoup does not parse or sanitize CSS.References