CVE-2023-26487
MEDIUMVega has cross-site scripting vulnerability in `lassoAppend` function
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
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
veganpmvega-functionsnpmDescription
Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs.lassoAppend' function accepts 3 arguments and internally invokes pushfunction on the 1st argument specifying array consisting of 2nd and 3rd arguments aspushcall argument. The type of the 1st argument is supposed to be an array, but it's not enforced. This makes it possible to specify any object with apushfunction as the 1st argument,pushfunction can be set to any function that can be access viaevent.view(no all such functions can be exploited due to invalid context or signature, but some can, e.g.console.log). The issue is thatlassoAppenddoesn't enforce proper types of its arguments. This issue opens various XSS vectors, but exact impact and severity depends on the environment (e.g. Core JSsetImmediatepolyfill basically allowseval`-like functionality). This issue was patched in 5.23.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | vega | all versions | 5.23.0 |
| 📦npm | vega-functions | all versions | 5.13.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 5.23.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-26487 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-2023-26487 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-2023-26487. 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-2023-26487 in your dependencies?
O3 detects CVE-2023-26487 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.