CVE-2025-62712

Executive Summary

CVE-2025-62712 is a critical authorization bypass vulnerability in JumpServer, an open-source bastion host and security audit system. The flaw resides in the /api/v1/authentication/super-connection-token/ API endpoint, which, when accessed from a web browser, returns connection tokens belonging to all users instead of only those owned by or authorized for the requester. An authenticated, non-privileged attacker can exploit this to retrieve tokens of other users, enabling unauthorized access to managed assets and privilege escalation. The vulnerability has a CVSS score of 9.6, indicating critical severity. No public proof-of-concept (PoC) or exploit code is currently available, but the risk is high due to the ease of exploitation and potential impact.

Supply Chain & Package Security

JumpServer is a Python-based open-source project distributed via GitHub and Docker. The vulnerability affects the core API logic, not a specific package dependency. However, organizations using JumpServer should verify the integrity of their deployment and ensure they are running a patched version. No malicious packages or compromised dependencies have been reported in relation to this CVE.

CVSS Breakdown & Threat Level

• CVSS Score: 9.6 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
• Attack Vector (AV): Network – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): Low – The attacker needs only a valid, non-privileged account.
• User Interaction (UI): None – No user action is needed.
• Scope (S): Changed – The vulnerability allows access to resources beyond the attacker’s intended authorization scope.
• Confidentiality (C): High – Full disclosure of connection tokens and potentially sensitive asset access.
• Integrity (I): High – The attacker can initiate connections as other users, altering session states.
• Availability (A): High – The attacker could disrupt or hijack connections.

Threat Level: Critical. The vulnerability allows an authenticated attacker to escalate privileges and gain unauthorized access to all managed assets, potentially leading to full compromise of the infrastructure.

Deep Dive & Mechanics

The vulnerability is an Insecure Direct Object Reference (IDOR) flaw, specifically CWE-639. The /api/v1/authentication/super-connection-token/ endpoint is designed to return connection tokens for the currently authenticated user. However, due to a missing authorization check, when the endpoint is accessed via a web browser (likely due to how the API handles session or request context), it returns tokens for all users in the system.

Root Cause: The API endpoint does not filter the database query by the requesting user’s identity. Instead, it returns all tokens stored in the database, assuming that only privileged users (e.g., admins) would access it. However, the endpoint is accessible to any authenticated user, and the browser-based access bypasses any intended client-side restrictions.

Attack Flow:

1. Attacker authenticates to JumpServer with a low-privileged account.
2. Attacker sends a GET request to /api/v1/authentication/super-connection-token/ from a browser (or with a browser-like User-Agent).
3. The server returns a JSON array containing connection tokens for all users.
4. Attacker extracts a token belonging to a privileged user (e.g., admin).
5. Attacker uses the token to initiate a connection to a managed asset, impersonating the token owner.
6. Attacker gains unauthorized access to sensitive systems, potentially escalating privileges further.

Impact: Full compromise of managed assets, lateral movement, and data exfiltration.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# views.py (vulnerable)
class SuperConnectionTokenView(APIView):
    def get(self, request):
        tokens = ConnectionToken.objects.all()  # No user filter
        serializer = ConnectionTokenSerializer(tokens, many=True)
        return Response(serializer.data)

Patched Code (Conceptual):

# views.py (patched)
class SuperConnectionTokenView(APIView):
    def get(self, request):
        tokens = ConnectionToken.objects.filter(user=request.user)  # Filter by user
        serializer = ConnectionTokenSerializer(tokens, many=True)
        return Response(serializer.data)

The patch adds a filter to ensure only tokens belonging to the requesting user are returned. Additionally, the endpoint may be restricted to admin users only in the patched version.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A valid JumpServer account with any role (e.g., user).
• Network access to the JumpServer web interface.

Exploitation Steps:

1. Log in to JumpServer as a low-privileged user.
2. Open browser developer tools (F12) and navigate to the Network tab.
3. Send a GET request to /api/v1/authentication/super-connection-token/.
4. Observe the response containing tokens for all users.
5. Copy a token belonging to an admin or privileged user.
6. Use the token to connect to a managed asset via the JumpServer client or API.

Example cURL command:

curl -X GET "https://jumpserver.example.com/api/v1/authentication/super-connection-token/" \
  -H "Authorization: Bearer <your_session_token>" \
  -H "User-Agent: Mozilla/5.0"

Expected Output:

[
  {
    "id": "token_1",
    "user": "admin",
    "asset": "server-01",
    "token": "eyJhbGciOiJIUzI1NiIs..."
  },
  {
    "id": "token_2",
    "user": "user1",
    "asset": "server-02",
    "token": "eyJhbGciOiJIUzI1NiIs..."
  }
]

Blue Team (Detection & Hardening)

Detection:

• Monitor API access logs for requests to /api/v1/authentication/super-connection-token/ from non-admin users.
• Alert on unusual token usage patterns, such as a token being used from a different IP or for an asset not normally accessed by the token owner.

Hardening:

• Immediately upgrade to JumpServer v3.10.20-lts or v4.10.11-lts.
• If patching is not possible, restrict access to the vulnerable endpoint via a reverse proxy (e.g., Nginx) to only allow requests from admin IPs.
• Implement additional logging and monitoring for the endpoint.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /api/v1/authentication/super-connection-token/ from non-admin users.
  • Unusual User-Agent strings (e.g., curl, python-requests) accessing the endpoint.
• Log IOCs:
  • JumpServer audit logs showing token retrieval by unexpected users.
  • Connection logs showing sessions initiated with tokens not belonging to the session user.
• File IOCs:
  • No specific file-based IOCs, but any unauthorized access to managed assets should be investigated.

Detection Engineering

YARA Rule

rule Detect_CVE_2025_62712_Exploit {
    meta:
        description = "Detects attempts to exploit CVE-2025-62712 by accessing the super-connection-token endpoint"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-62712"
    strings:
        $endpoint = "/api/v1/authentication/super-connection-token/"
        $token_pattern = /"token"\s*:\s*"eyJ[A-Za-z0-9_-]+\.eyJ[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+"/  // JWT token pattern
    condition:
        $endpoint and $token_pattern
}

Sigma Rule

title: JumpServer Super Connection Token Access by Non-Admin User
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects when a non-admin user accesses the super-connection-token API endpoint, indicating potential exploitation of CVE-2025-62712.
author: Valters IT
date: 2025-04-10
logsource:
    category: web
    product: jumpserver
detection:
    selection:
        http.url: "/api/v1/authentication/super-connection-token/"
        http.method: "GET"
        user.role: "user"  # Adjust based on actual role field
    condition: selection
falsepositives:
    - Legitimate admin access (should be filtered by role)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-62712 JumpServer Super Connection Token Access"; flow:to_server; content:"GET"; http_method; content:"/api/v1/authentication/super-connection-token/"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Upgrade to JumpServer v3.10.20-lts or v4.10.11-lts immediately.
2. Workaround: If patching is delayed, restrict access to the vulnerable endpoint using a reverse proxy or firewall rule to allow only admin IPs.
3. Audit: Review logs for any signs of exploitation. Rotate all connection tokens and force password resets for all users.

Long-Term Measures:

• Implement strict API authorization checks for all endpoints.
• Conduct regular security audits and penetration testing.
• Monitor for similar IDOR vulnerabilities in other parts of the application.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.