CVE-2026-70599 is a medium-severity (CVSS 5.9) CWE-346 vulnerability in electron. O3 Security confirms whether CVE-2026-70599 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Electron: Permission Check Handler Receives Main Frame Origin Instead of Requesting Iframe Origin
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 CVE-2026-70599.
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
CVE-2026-70599 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 368,634 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.
electronnpmDescription
Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 39.8.7, 40.9.0, 41.2.0, and 42.0.0-beta.1, serial-port and media permission checks made from an iframe passed the top-level frame origin to session.setPermissionCheckHandler instead of the requesting iframe origin. Origin-based handler logic could grant a cross-origin iframe device access intended only for the top-level origin. This issue is fixed in 39.8.7, 40.9.0, 41.2.0, and 42.0.0-beta.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | electron | all versions | 39.8.7 |
| 📦npm | electron | ≥ 40.0.0-alpha.1&&< 40.9.0 | 40.9.0 |
| 📦npm | electron | ≥ 41.0.0-alpha.1&&< 41.2.0 | 41.2.0 |
| 📦npm | electron | ≥ 42.0.0-alpha.1&&< 42.0.0-beta.1 | 42.0.0-beta.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for electron. 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 electron to 39.8.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-70599 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-2026-70599 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-2026-70599. 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-2026-70599 in your dependencies?
O3 detects CVE-2026-70599 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.