CVE-2025-11713 is a security vulnerability identified in Mozilla Firefox and Thunderbird on Windows platforms, specifically affecting versions of Firefox prior to 144 and ESR versions prior to 140.4, as well as Thunderbird versions prior to 144 and ESR versions prior to 140.4. The vulnerability arises from insufficient escaping in the “Copy as cURL” feature, which is designed to allow users to copy HTTP requests as cURL commands for debugging or scripting purposes. Due to improper escaping, an attacker can craft a malicious HTTP request that, when copied using the “Copy as cURL” command and subsequently executed by the user in a Windows command-line environment, could lead to execution of arbitrary code. This is a user-assisted code execution vulnerability, meaning exploitation requires social engineering to convince the user to perform the copy and execute the command. The flaw is specific to Windows because of how command-line parsing and escaping are handled in that environment; other operating systems are not affected. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability affects both Firefox and Thunderbird products, which are widely used in both consumer and enterprise environments. The lack of proper escaping in the cURL command generation can allow injection of command-line instructions that execute unintended commands, potentially compromising system integrity and confidentiality. This vulnerability highlights the risks associated with features that generate executable commands from user data without sufficient sanitization.

For European organizations, the impact of CVE-2025-11713 can be significant, particularly for those relying on Firefox and Thunderbird on Windows platforms. Successful exploitation could lead to arbitrary code execution on user machines, potentially allowing attackers to install malware, steal sensitive information, or move laterally within corporate networks. Since the attack requires user interaction, the risk is elevated in environments where users frequently use the “Copy as cURL” feature for development, debugging, or automation tasks. The vulnerability could be leveraged in targeted phishing campaigns or social engineering attacks aimed at IT staff or developers. The compromise of endpoints could disrupt business operations, lead to data breaches, and damage organizational reputation. Given the widespread use of Firefox and Thunderbird in European enterprises, especially in sectors like finance, government, and technology, the threat could affect critical infrastructure and sensitive data. The Windows-specific nature of the vulnerability means organizations with predominantly Windows endpoints are at higher risk. Although no exploits are currently known, the potential for exploitation once a proof-of-concept is developed necessitates proactive mitigation.

1. Immediate patching: Organizations should monitor Mozilla’s security advisories and apply updates to Firefox and Thunderbird as soon as fixed versions (>= Firefox 144 and ESR 140.4) are released. 2. User education: Train users, especially developers and IT personnel, to be cautious when copying and executing commands from untrusted sources, emphasizing the risks of executing copied cURL commands without verification. 3. Restrict command execution: Implement endpoint protection policies that restrict execution of commands from user clipboard data or unknown scripts, particularly on Windows systems. 4. Use application whitelisting: Employ application control solutions to prevent unauthorized or suspicious command-line executions. 5. Network monitoring: Deploy monitoring to detect unusual command-line activities or suspicious network requests that could indicate exploitation attempts. 6. Disable or limit use of the “Copy as cURL” feature in environments where it is not essential, or provide alternative safe tools for HTTP request inspection. 7. Encourage use of non-Windows platforms for development tasks involving cURL commands when feasible, as the vulnerability does not affect other OSes. 8. Maintain up-to-date backups and incident response plans to quickly recover from potential compromises.