Package Instance

TYPO3 HTML Sanitizer Bypasses Cross-Site Scripting Protection
> ### Meta
> * CVSS: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C` (5.7)

### Problem
Due to a parsing issue in upstream package [`masterminds/html5`](https://packagist.org/packages/masterminds/html5), malicious markup used in a sequence with special HTML comments cannot be filtered and sanitized. This allows to by-pass the cross-site scripting mechanism of `typo3/html-sanitizer`.

### Solution
Update to `typo3/html-sanitizer` versions 1.0.7 or 2.0.16 that fix the problem described.

### Credits
Thanks to David Klein who reported this issue, and to TYPO3 security team member Oliver Hader who fixed the issue.

Bypassing Cross-Site Scripting Protection in TYPO3 HTML Sanitizer
TYPO3 is an open source PHP based web content management system released under the GNU GPL. In affected versions DOM processing instructions are not handled correctly. This allows bypassing the cross-site scripting mechanism of typo3/html-sanitizer. This vulnerability has been addressed in versions 1.5.3 and 2.1.4. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
TYPO3 HTML Sanitizer is an HTML sanitizer, written in PHP, aiming to provide cross-site-scripting-safe markup based on explicitly allowed tags, attributes and values. Starting in version 1.0.0 and prior to versions 1.5.1 and 2.1.2, due to an encoding issue in the serialization layer, malicious markup nested in a `noscript` element was not encoded correctly. `noscript` is disabled in the default configuration, but might have been enabled in custom scenarios. This allows bypassing the cross-site scripting mechanism of TYPO3 HTML Sanitizer. Versions 1.5.1 and 2.1.2 fix the problem.

TYPO3 HTML Sanitizer vulnerable to Cross-Site Scripting
### Problem
Due to a parsing issue in the upstream package [`masterminds/html5`](https://packagist.org/packages/masterminds/html5), malicious markup used in a sequence with special HTML CDATA sections cannot be filtered and sanitized. This allows bypassing the cross-site scripting mechanism of [`typo3/html-sanitizer`](https://packagist.org/packages/typo3/html-sanitizer).

Besides that, the upstream package `masterminds/html5` provides HTML raw text elements (`script`, `style`, `noframes`, `noembed` and `iframe`) as DOMText nodes, which were not processed and sanitized further. None of the mentioned elements were defined in the default builder configuration, that's why only custom behaviors, using one of those tag names, were vulnerable to cross-site scripting.

### Solution
Update to `typo3/html-sanitizer` versions 1.5.0 or 2.1.1 that fix the problem described.