CVE-2025-11713 is a vulnerability identified in Mozilla Firefox and Thunderbird affecting Windows platforms due to insufficient escaping in the 'Copy as cURL' feature. This feature allows users to copy HTTP requests as cURL commands for debugging or scripting purposes. The vulnerability arises because the escaping of special characters in the generated cURL command is inadequate, enabling an attacker to craft malicious input that, when copied and executed by the user, could run arbitrary code on the victim's machine. This attack vector requires user interaction, specifically the user executing the copied command in a Windows environment. The flaw does not affect Firefox or Thunderbird on other operating systems due to differences in command execution contexts. Affected versions include Firefox versions below 144, Firefox ESR below 140.4, Thunderbird below 144, and Thunderbird ESR below 140.4. The vulnerability is categorized under CWE-116 (Improper Encoding or Escaping of Output). The CVSS v3.1 base score is 8.1, indicating high severity, with an attack vector of network, low attack complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality and integrity but no impact on availability. No public exploits have been reported yet, but the potential for exploitation exists given the nature of the vulnerability and the widespread use of Firefox and Thunderbird on Windows. The vulnerability was published on October 14, 2025, and is currently in a published state without available patches at the time of this report.

For European organizations, this vulnerability poses a significant risk primarily to Windows users of Firefox and Thunderbird who utilize the 'Copy as cURL' feature. Successful exploitation could lead to arbitrary code execution, compromising confidentiality and integrity of sensitive data and potentially enabling further lateral movement or persistence within corporate networks. Organizations relying on these browsers for web access or email communications may face targeted attacks leveraging this vulnerability, especially in sectors with high security requirements such as finance, government, and critical infrastructure. The requirement for user interaction limits automated exploitation but does not eliminate risk, as social engineering or phishing campaigns could trick users into executing malicious commands. The absence of impact on availability reduces the likelihood of denial-of-service conditions but does not mitigate the risk of data breaches or system compromise. Given the widespread adoption of Firefox and Thunderbird across Europe, the vulnerability could affect a large number of endpoints, increasing the potential attack surface. Additionally, organizations with development or security teams frequently using cURL commands for testing or automation are at elevated risk.

1. Immediately monitor Mozilla's official channels for patches addressing CVE-2025-11713 and apply updates to Firefox and Thunderbird to versions 144/140.4 or later as soon as they become available. 2. Until patches are released, consider disabling or restricting the use of the 'Copy as cURL' feature in Firefox and Thunderbird through configuration policies or group policy objects where possible. 3. Educate users about the risks of executing copied commands from untrusted sources, emphasizing caution when using the 'Copy as cURL' feature and running command-line instructions. 4. Implement endpoint security solutions capable of detecting and blocking suspicious command-line executions that may result from exploitation attempts. 5. Employ network-level protections such as email filtering and web gateway controls to reduce the likelihood of phishing or social engineering attacks delivering malicious payloads. 6. Conduct targeted awareness campaigns for IT and security teams to recognize and respond to potential exploitation attempts involving this vulnerability. 7. Audit and restrict user permissions to limit the impact of potential code execution, ensuring users operate with least privilege. 8. Monitor logs and endpoint telemetry for unusual command executions or behavior indicative of exploitation attempts related to cURL commands.