CVE-2026-112942

### Summary `launch-editor` checked `fs.existsSync(fileName)` before passing a supplied path to an editor command. On Windows, an attacker can bypass this check with a crafted path ending in `\\..:line:column`. This removes the requirement that the attacker be able to place a file with a malicious filename. Combined with the `%` escaping issue described in [GHSA-698v-4r3x-3vcv](https://github.com/vitejs/launch-editor/security/advisories/GHSA-698v-4r3x-3vcv), this bypass can lead to OS command injection when an attacker controls the file argument. ### Impact Only apps that runs on Windows is affected. ### Details The earlier advisory assumed that `fs.existsSync()` required an attacker-controlled filename to exist. This advisory covers a bypass of that requirement. A crafted value ending in `\\..:1:1` is interpreted differently by `launch-editor-middleware`, `launch-editor`, and Windows: 1. `launch-editor-middleware` calls `path.resolve()` while the final path component is `..:1:1`, so it is not treated as a parent-directory component. 2. `launch-editor` treats `:1:1` as a line-and-column suffix and removes it, leaving a path ending in `\\..`. 3. On Windows, `fs.existsSync()` accepts the resulting path as the existing parent directory even though the attacker-controlled preceding component does not exist. 4. Because the existence check passes, the crafted filename reaches the Windows shell command.