Overview
The Common Vulnerabilities and Exposures system (CVE) has identified a significant security flaw in the popular Themeton Spare software. This vulnerability, categorized as CVE-2025-31919, poses a serious risk to any systems running versions of Spare up to 1.7.
The vulnerability revolves around the deserialization of untrusted data, which can lead to Object Injection. If exploited, this could result in a full system compromise or data leakage. Given the widespread use of Themeton Spare, this issue demands immediate attention from system administrators and security teams.
Vulnerability Summary
CVE ID: CVE-2025-31919
Severity: Critical (9.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
Themeton Spare | Up to 1.7
How the Exploit Works
The vulnerability is based on the software’s insecure handling of serialized or “flattened” data. During the deserialization process, the software fails to properly validate or sanitize the incoming data. This allows an attacker to inject malicious objects into the data stream, which are then executed when the data is deserialized.
An attacker can exploit this vulnerability remotely, over the network, without requiring any special privileges or user interaction. If successfully exploited, the attacker gains control of the system and may also gain access to sensitive data.
Conceptual Example Code
The following is a conceptual example of how an attacker might exploit this vulnerability. This is not an actual exploit code, but rather a demonstration of the type of malicious payload that could be used.
POST /deserialization-endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "serialized_object": "rO0ABXNyADJjb20udGhlbWV0b24uc3BhcmUuRXhhbXBsZU9iamVjdEV4cGxvaXQAAAAAAAAAAQIAAHhyADFjb20udGhlbWV0b24uc3BhcmUuRXhhbXBsZU9iamVjdAAAAAAAAAABAgAAeHAAAAAA=" }In this example, the “serialized_object” field contains a Base64-encoded serialized object that includes malicious code. When the server deserializes this object, the malicious code is executed, leading to a potential system compromise.
Mitigation Guidance
Until a patch is available from the vendor, security teams are advised to implement a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block attempts to exploit this vulnerability. These systems can be configured to identify and stop potentially malicious deserialization operations, providing a temporary mitigation for this issue.