CVE-2025-27287: Critical Deserialization of Untrusted Data Vulnerability in SS Quiz

Overview

In today’s post, we delve into an alarming vulnerability identified as CVE-2025-27287. This severe security flaw resides in the popular software, ssvadim SS Quiz, versions up to and including 2.0.5. The issue lies in the deserialization of untrusted data, which allows for object injection. Given the ubiquity of SS Quiz in numerous systems, this vulnerability has the potential to affect a wide scope of users and organizations.
The relevance of this vulnerability cannot be overstated. It scores a high 9.8 on the CVSS Severity Scale, indicating its severe threat level. Exploitation of this vulnerability can lead to system compromise and data leakage – a nightmare scenario for any system administrator or user.

Vulnerability Summary

CVE ID: CVE-2025-27287
Severity: Critical (9.8/10)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise, data leakage

Affected Products

Product | Affected Versions

ssvadim SS Quiz | n/a through 2.0.5

How the Exploit Works

The vulnerability arises from the application’s failure to properly validate and sanitize user-supplied input during the data deserialization process. In a nutshell, deserialization is the process of converting serialized data from a complex object to a stream of bytes, and back into the object. In this case, an attacker can inject malicious serialized objects into the application. When the application deserializes these malicious objects, it can execute harmful actions, potentially leading to full system compromise or data leakage.

Conceptual Example Code

Here’s a simplified conceptual example of how the vulnerability might be exploited. An attacker could send a specially crafted HTTP request to the vulnerable endpoint, like this:

POST /ssquiz/submitQuiz HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "serializedObject": "rO0ABXNyAC5qYXZhLnV0aWwuSGFzaE1hcAUH2sHDFmDRAwACRgAKbG9hZEZhY3RvckkACXRocmVzaG9sZHhwP0AAAAAAAAx3CAAAABAAAAAAeHg=" }

In this example, the serializedObject field contains a Base64 encoded serialized object. If the object’s class has a readObject method, the method will be executed upon deserialization, leading to the execution of potentially malicious code.

Mitigation

The most direct mitigation for this vulnerability is to apply patches provided by the vendor. If patches are not available or cannot be applied immediately, it is recommended to use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and block potential exploit attempts.