CVE-2026-34778 — electron
MEDIUMCVE-2026-34778 is a medium-severity (CVSS 5.9) CWE-290 vulnerability in electron. A fix is available for electron — see the affected versions and patch details below.
Electron: Service worker can spoof executeJavaScript IPC replies
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-2026-34778.
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-2026-34778 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 377,636 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
Impact
A service worker running in a session could spoof reply messages on the internal IPC channel used by webContents.executeJavaScript() and related methods, causing the main-process promise to resolve with attacker-controlled data.
Apps are only affected if they have service workers registered and use the result of webContents.executeJavaScript() (or webFrameMain.executeJavaScript()) in security-sensitive decisions.
Workarounds
Do not trust the return value of webContents.executeJavaScript() for security decisions. Use dedicated, validated IPC channels for security-relevant communication with renderers.
Fixed Versions
41.0.040.8.139.8.138.8.6
For more information
If there are any questions or comments about this advisory, please email [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | electron | all versions | 38.8.6npm install electron@38.8.6 |
| 📦npm | electron | ≥ 39.0.0-alpha.1&&< 39.8.1 | 39.8.1npm install electron@39.8.1 |
| 📦npm | electron | ≥ 40.0.0-alpha.1&&< 40.8.1 | 40.8.1npm install electron@40.8.1 |
| 📦npm | electron | ≥ 41.0.0-alpha.1&&< 41.0.0 | 41.0.0npm install electron@41.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for electron, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update electron to 38.8.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34778 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34778 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34778. 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-2026-34778 in your dependencies?
O3 Security finds CVE-2026-34778 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.