GHSA-8775-5hwv-wr6v is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in posthog-js. A fix is available for posthog-js — see the affected versions and patch details below.
Potential for cross-site scripting in PostHog-js
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-8775-5hwv-wr6v.
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-8775-5hwv-wr6v 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
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
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 | 1.57.2npm install posthog-js@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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-8775-5hwv-wr6v can be triaged on real exposure rather than presence alone.
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 Security finds GHSA-8775-5hwv-wr6v across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.