GHSA-g955-vw6w-v6pp — starcitizentools/citizen-…
MEDIUMFix: StarCitizenTools/mediawiki-skins-Citizen@e006923GHSA-g955-vw6w-v6pp is a medium-severity (CVSS 6.5) Cross-site Scripting (XSS) vulnerability in starcitizentools/citizen-skin. A fix is available for starcitizentools/citizen-skin — see the affected versions and patch details below.
Citizen vulnerable to stored XSS in sticky header button messages
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.
Exploitation and automatability from CISA’s SSVC triage for GHSA-g955-vw6w-v6pp.
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-g955-vw6w-v6pp 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 379,145 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
starcitizentools/citizen-skinReal-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 JS implementation for copying button labels to the sticky header in the Citizen skin unescapes HTML characters, allowing for stored XSS through system messages.
Details
In the copyButtonAttributes function in stickyHeader.js, when copying the button labels, the innerHTML of the new element is set to the textContent of the old element:
https://github.com/StarCitizenTools/mediawiki-skins-Citizen/blob/f4cbcecf5aca0ae69966b23d4983f9cb5033f319/resources/skins.citizen.scripts/stickyHeader.js#L29-L41
This unescapes any escaped HTML characters and causes the contents of the system messages to be interpreted as HTML.
PoC
- Edit any of the affected messages (
citizen-share,citizen-view-history,citizen-view-edit,nstab-talk) to the following payload:<img src="" onerror="alert('Sticky Header Button XSS')">. - Visit any mainpage article in the wiki using the Citizen skin.
Impact
This impacts wikis where a group has the editinterface but not the editsitejs user right. By default, this is the case for the sysop group.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | starcitizentools/citizen-skin | ≥ 3.3.0&&< 3.9.0 | 3.9.0composer require starcitizentools/citizen-skin:^3.9.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for starcitizentools/citizen-skin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update starcitizentools/citizen-skin to 3.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g955-vw6w-v6pp 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-g955-vw6w-v6pp can be triaged on real exposure rather than presence alone.
Tailored to GHSA-g955-vw6w-v6pp. 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-g955-vw6w-v6pp in your dependencies?
O3 Security finds GHSA-g955-vw6w-v6pp across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.