GHSA-hg8h-557g-q8pp — mediawiki/semantic-media-…
HIGHGHSA-hg8h-557g-q8pp is a high-severity (CVSS 8.6) Cross-site Scripting (XSS) vulnerability in mediawiki/semantic-media-wiki. A fix is available for mediawiki/semantic-media-wiki — see the affected versions and patch details below.
Semantic MediaWiki vulnerable to stored XSS through wikitext via improper use of non-reserved data attributes
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hg8h-557g-q8pp.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-hg8h-557g-q8pp plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
mediawiki/semantic-media-wikiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The SemanticMediaWiki extension inserts the unsanitized value of a data attribute into the DOM as HTML, allowing for stored XSS through wikitext.
Details
In ext.smw.js, the data-subtab attribute of all elements with the smw-subtab class is parsed as JSON and appended to the innerHTML of the element:
https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/62f1fa765b626e21d88999b97a3e8029db9fd385/res/smw/ext.smw.js#L37-L42
However, most data attributes (except for reserved ones) like data-subtab can be used in wikitext. Therefore, it is possible to insert arbitrary HTML and JS through wikitext.
The decoded (" will turn to ", but it will be decoded when it is retrieved through .dataset) value of the data-subtab attribute in the payload is "<img src='' onerror=alert(1)>". This is valid JSON and returns a string with <img src='' onerror=alert(1)> when being decoded.
PoC
- Create a page with the following contents:
{{#tag:div|
|class=smw-subtab
|data-subtab=""<img src='' onerror=alert(1)>""
}}
- Visit the page
Impact
Arbitrary HTML can be inserted into the DOM by any user with the edit right, allowing for JavaScript to be executed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mediawiki/semantic-media-wiki | ≥ 3.1.0&&< 7.0.0 | 7.0.0composer require mediawiki/semantic-media-wiki:^7.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mediawiki/semantic-media-wiki, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mediawiki/semantic-media-wiki to 7.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hg8h-557g-q8pp is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-hg8h-557g-q8pp can be triaged on real exposure rather than presence alone.
Tailored to GHSA-hg8h-557g-q8pp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-hg8h-557g-q8pp in your dependencies?
O3 Security finds GHSA-hg8h-557g-q8pp across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.