CVE-2026-70603

Electron: shell.openPath path validation bypass via embedded null byte

Workarounds

Reject any path containing a null byte before passing it to shell.openPath():

if (filePath.includes('\0')) throw new Error('invalid path');

Fixed Versions

• 42.0.0-beta.1
• 41.1.1
• 40.9.0
• 39.8.6

For more information

If you have any questions or comments about this advisory, email us at [email protected]

shell.openPath() did not reject paths containing embedded null bytes. Apps that perform string-only validation of file paths (for example, checking the file extension) before passing them to shell.openPath() could be bypassed, allowing an attacker-controlled path to open a different file than the one that passed validation.

Apps are only affected if they pass paths derived from untrusted input to shell.openPath() and rely on string-based validation without a filesystem check. Node's fs APIs already reject paths containing null bytes, so apps that call fs.existsSync(), fs.stat(), or similar before shell.openPath() are not affected. Apps that do not call shell.openPath() with untrusted input are not affected.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-70603 has a CVSS score of 6.0 (Medium). The vector is requires local access, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (42.0.0-beta.1, 41.1.1, 40.9.0, 39.8.6); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2026-70603? CVE-2026-70603 is a medium-severity improper input validation vulnerability in electron (npm), affecting versions >= 42.0.0-alpha.1, < 42.0.0-beta.1. It is fixed in 42.0.0-beta.1, 41.1.1, 40.9.0, 39.8.6. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-70603? CVE-2026-70603 has a CVSS score of 6.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of electron are affected by CVE-2026-70603? electron (npm) versions >= 42.0.0-alpha.1, < 42.0.0-beta.1 is affected.
4. Is there a fix for CVE-2026-70603? Yes. CVE-2026-70603 is fixed in 42.0.0-beta.1, 41.1.1, 40.9.0, 39.8.6. Upgrade to this version or later.
5. Is CVE-2026-70603 exploitable, and should I be worried? Whether CVE-2026-70603 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-70603 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-70603?
   • Upgrade electron to 42.0.0-beta.1 or later
   • Upgrade electron to 41.1.1 or later
   • Upgrade electron to 40.9.0 or later
   • Upgrade electron to 39.8.6 or later

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