CVE-2026-55690 is a high-severity (CVSS 7.5) vulnerability in starcitizenwiki/embedvideo. O3 Security confirms whether CVE-2026-55690 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
StarCitizenWiki Extension Embed Video: Stored XSS via unsanitized service name in exception text
Real-World Exposure
starcitizenwiki/embedvideoReal-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
When passing an unknown service name to embedvideo, an error message is rendered containing the invalid service name. The service name is not sanitized and can contain HTML.
Details
There is a hardcoded list of allowed services in a switch statement inside EmbedServiceFactory#newFromName here. When the service name is not known, an exception is thrown with the service name injected into the message via sprintf here. This message is not sanitized and is marked as isHtml here. Similarly with {{evl: here.
PoC
// Must be on a page, not on ExpandTemplates
{{#ev:<img src=x onerror=alert(document.domain)>|dQw4w9WgXcQ}}
{{#evl:id=dummy|service=<img src=x onerror=alert(document.domain)>}}
Impact
Stored XSS that allows arbitrary Javascript/HTML insertion on any page that a user can edit. It requires no interaction and executes in the wiki origin for every visitor to the page.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | starcitizenwiki/embedvideo | all versions | 4.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for starcitizenwiki/embedvideo. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update starcitizenwiki/embedvideo to 4.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55690 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 pinpoints whether CVE-2026-55690 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55690. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55690 in your dependencies?
O3 detects CVE-2026-55690 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.