Headline
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:
- Go to Special:ExpandTemplates and insert the following wikitext:
<tabber class='test123" onmouseenter="alert(1)"'>
|-|First Tab Title=
First tab content goes here.
</tabber>
- Press “OK”
- Hover over the tabber
XSS through script tags:
- Go to Special:ExpandTemplates and insert the following wikitext:
<tabber class='test123"><script>alert(2)</script>'>
|-|First Tab Title=
First tab content goes here.
</tabber>
- Press “OK”
Impact
Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.
Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.