GHSA-jfj7-249r-7j2m

TabberNeue vulnerable to Stored XSS through wikitext

### Summary Arbitrary HTML can be inserted into the DOM by inserting a payload into any allowed attribute of the `<tabber>` tag. ### Details The `args` provided within the wikitext as attributes to the `<tabber>` tag are passed to the TabberComponentTabs class: https://github.com/StarCitizenTools/mediawiki-extensions-TabberNeue/blob/3a23b703ce36cfc4128e7921841f68230be4059a/includes/Tabber.php#L76 In TabberComponentTabs, the attributes are validated before being supplied to the Tabs template. https://github.com/StarCitizenTools/mediawiki-extensions-TabberNeue/blob/3a23b703ce36cfc4128e7921841f68230be4059a/includes/Components/TabberComponentTabs.php#L15-L31 However, the validation is insufficient. What `Sanitizer::validateTagAttributes` does is call `validateAttributes`, which ``` * - Discards attributes not on the given list * - Unsafe style attributes are discarded * - Invalid id attributes are re-encoded ``` However, the attribute values are expected to be escaped when inserted into HTML. The attribute values are then inserted into HTML without being escaped: https://github.com/StarCitizenTools/mediawiki-extensions-TabberNeue/blob/3a23b703ce36cfc4128e7921841f68230be4059a/includes/templates/Tabs.mustache#L1 ### PoC #### XSS through attributes: 1. Go to Special:ExpandTemplates and insert the following wikitext: ``` <tabber class='test123" onmouseenter="alert(1)"'> |-|First Tab Title= First tab content goes here. </tabber> ``` 2. Press "OK" 3. Hover over the tabber  #### XSS through script tags: 1. Go to Special:ExpandTemplates and insert the following wikitext: ``` <tabber class='test123"&gt;&lt;script&gt;alert(2)&lt;/script&gt;'> |-|First Tab Title= First tab content goes here. </tabber> ``` 2. Press "OK"  ### Impact Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.