CVE-2026-34773

Workarounds

Validate the protocol name matches /^[a-zA-Z][a-zA-Z0-9+.-]*$/ before passing it to app.setAsDefaultProtocolClient().

Fixed Versions

• 41.0.0
• 40.8.1
• 39.8.1
• 38.8.6

For more information

If there are any questions or comments about this advisory, please email [email protected]

On Windows, app.setAsDefaultProtocolClient(protocol) did not validate the protocol name before writing to the registry. Apps that pass untrusted input as the protocol name may allow an attacker to write to arbitrary subkeys under HKCU\Software\Classes\, potentially hijacking existing protocol handlers.

Apps are only affected if they call app.setAsDefaultProtocolClient() with a protocol name derived from external or untrusted input. Apps that use a hardcoded protocol name 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-2026-34773 has a CVSS score of 4.7 (Medium). The vector is requires local access, low privileges required, and no user interaction. 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 (38.8.6, 39.8.1, 40.8.1, 41.0.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-34773? CVE-2026-34773 is a medium-severity improper input validation vulnerability in electron (npm), affecting versions < 38.8.6. It is fixed in 38.8.6, 39.8.1, 40.8.1, 41.0.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-34773? CVE-2026-34773 has a CVSS score of 4.7 (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-2026-34773? electron (npm) versions < 38.8.6 is affected.
4. Is there a fix for CVE-2026-34773? Yes. CVE-2026-34773 is fixed in 38.8.6, 39.8.1, 40.8.1, 41.0.0. Upgrade to this version or later.
5. Is CVE-2026-34773 exploitable, and should I be worried? Whether CVE-2026-34773 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-2026-34773 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-2026-34773?
   • Upgrade electron to 38.8.6 or later
   • Upgrade electron to 39.8.1 or later
   • Upgrade electron to 40.8.1 or later
   • Upgrade electron to 41.0.0 or later