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CVE-2025-54796: Copyparty File Server Vulnerability Leading to Potential System Compromise

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Overview

This report provides an analysis of a significant vulnerability in Copyparty, a widely-utilized portable file server. Identified as CVE-2025-54796, this vulnerability could allow an attacker to deadlock the server, potentially compromising the system or leading to data leakage. It is critical for organizations using affected versions of Copyparty to understand the implications of this vulnerability and take immediate actions to mitigate potential risks.

Vulnerability Summary

CVE ID: CVE-2025-54796
Severity: High (7.5 CVSS)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System deadlock leading to potential system compromise or data leakage

Affected Products

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Product | Affected Versions

Copyparty | Up to but not including 1.18.9

How the Exploit Works

The vulnerability resides in the filter parameter for the “Recent Uploads” page in versions of Copyparty prior to 1.18.9. This parameter allows arbitrary RegExes. If this feature is enabled (which is the default setting), an attacker can craft a filter introducing a complex enough regular expression that would cause the server to enter into an infinite loop or consume excessive resources, thus deadlocking the server.

Conceptual Example Code

The following pseudocode exemplifies how an attacker might exploit this vulnerability:

GET /recent-uploads?filter=(a+)+b HTTP/1.1
Host: target.example.com

In this example, the filter `(a+)+b` is a classic example of a regular expression that can lead to catastrophic backtracking, causing the server to consume excessive resources and enter a deadlock state.

Mitigation

For mitigation, it’s recommended to upgrade to Copyparty version 1.18.9 or later where this vulnerability has been fixed. As a temporary countermeasure, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can be configured to block or filter requests containing complex or potentially malicious regular expressions.

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Disclaimer:

The information and code presented in this article are provided for educational and defensive cybersecurity purposes only. Any conceptual or pseudocode examples are simplified representations intended to raise awareness and promote secure development and system configuration practices.

Do not use this information to attempt unauthorized access or exploit vulnerabilities on systems that you do not own or have explicit permission to test.

Ameeba and its authors do not endorse or condone malicious behavior and are not responsible for misuse of the content. Always follow ethical hacking guidelines, responsible disclosure practices, and local laws.

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