GHSA-8775-5hwv-wr6v is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in posthog-js. O3 Security confirms whether GHSA-8775-5hwv-wr6v is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Potential for cross-site scripting in PostHog-js
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
posthog-jsnpmDescription
Impact
Potential for cross-site scripting in posthog-js.
Patches
The problem has been patched in posthog-js version 1.57.2.
Workarounds
- This isn't an issue for sites that have a Content Security Policy in place.
- Using the HTML tracking snippet on PostHog Cloud always guarantees the latest version of the library – in that case no action is required to upgrade to the patched version.
References
We will publish details of the vulnerability in 30 days as per our security policy.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | posthog-js | all versions | 1.57.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for posthog-js. 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 posthog-js to 1.57.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8775-5hwv-wr6v 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 GHSA-8775-5hwv-wr6v 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 GHSA-8775-5hwv-wr6v. 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-8775-5hwv-wr6v in your dependencies?
O3 detects GHSA-8775-5hwv-wr6v across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.