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

Impact

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.

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

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