CVE-2025-40738: Critical Arbitrary File Write Vulnerability in SINEC NMS

Overview

The vulnerability CVE-2025-40738 is a critical security flaw affecting SINEC NMS, which potentially exposes the systems to significant risks. This vulnerability is a particular concern for system administrators and security professionals because SINEC NMS is widely used in various industries for network management. The flaw leverages the application’s improper validation of file paths when extracting uploaded ZIP files, allowing attackers to write arbitrary files to restricted locations and potentially execute code with elevated privileges. This loophole can compromise the system and lead to data leakage, hence warranting immediate attention.

Vulnerability Summary

CVE ID: CVE-2025-40738
Severity: Critical (8.8 CVSS)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: Compromise of system and potential data leakage

Affected Products

Product | Affected Versions

SINEC NMS | All versions < V4.0 How the Exploit Works

The vulnerability stems from the application’s failure to accurately validate file paths when extracting uploaded ZIP files. An attacker can exploit this by uploading a specially crafted ZIP file with a manipulated file path. When the system extracts the ZIP file, the attacker’s file is written to an arbitrary, restricted location. If the location is within a PATH directory or if it overwrites a sensitive file, the attacker might be able to execute arbitrary code with the privileges of the application.

Conceptual Example Code

This is a conceptual example of how the vulnerability might be exploited. The attacker crafts a ZIP file that, when extracted, writes a malicious file to a restricted location.

$ zip malicious.zip -r .
$ echo "echo 'malicious_code' > /restricted/path/to/file" > payload.sh
$ zip malicious.zip payload.sh

Then, the attacker would upload this ZIP file to the vulnerable endpoint.

POST /upload/zip HTTP/1.1
Host: target.example.com
Content-Type: application/zip
Content-Length: [length of zip file]
[binary data of zip file]

If the server is configured to automatically extract uploaded ZIP files to a directory within its PATH, the payload script could be executed, leading to arbitrary code execution.

Mitigation

The immediate mitigation for this vulnerability is to apply the vendor-provided patch. If the patch cannot be applied immediately, use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to monitor and filter out malicious payloads. Regularly review and update security policies to ensure the system is protected against such vulnerabilities.