Overview
The vulnerability designated as CVE-2025-35940 is a critical flaw discovered in the ArchiverSpaApi ASP.NET application. This application’s security vulnerability arises from the use of a hard-coded JSON Web Token (JWT) signing key. The flaw potentially affects all entities that utilize the affected application, and could lead to unauthorized access, system compromise, or data leakage. The severity of this vulnerability highlights the importance of robust cybersecurity practices, especially in the area of access control and authentication management.
Vulnerability Summary
CVE ID: CVE-2025-35940
Severity: High (CVSS: 8.1)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Unauthorized access to protected API endpoints, potential system compromise and data leakage
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Product | Affected Versions
ArchiverSpaApi ASP.NET Application | All versions prior to the patch
How the Exploit Works
The CVE-2025-35940 vulnerability stems from the application’s use of a hard-coded JWT signing key. This key is used to verify the integrity of JWT tokens, which are often used for user authentication and access control. An attacker with knowledge of this key can generate and sign their own JWT tokens. These tokens would be accepted as valid by the application, granting the attacker access to protected API endpoints.
Conceptual Example Code
An attacker might exploit this vulnerability via a HTTP request like the one below. In this example, the attacker crafts a malicious JWT token (“eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9…”) using the hard-coded signing key and includes it in the Authorization header:
POST /protected/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
{ "malicious_payload": "..." }This request would be accepted by the server as if it were from an authenticated user, allowing the attacker to perform actions or access data they should not be able to.
Guidance on Mitigation and Patching
The recommended mitigation for this vulnerability is to apply the vendor-supplied patch, which replaces the hard-coded signing key with a secure, randomly generated one. If the patch cannot be applied immediately, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can be used as a temporary mitigation measure. These systems can be configured to block requests containing known malicious JWT tokens. However, this is a stop-gap measure and not a full solution; the vendor’s patch should be applied as soon as possible.