CVE-2025-5264 in Firefox
Summary
by MITRE • 05/27/2025
Due to insufficient escaping of the newline character in the “Copy as cURL” feature, an attacker could trick a user into using this command, potentially leading to local code execution on the user's system. This vulnerability affects Firefox < 139, Firefox ESR < 115.24, and Firefox ESR < 128.11.
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Analysis
by VulDB Data Team • 08/16/2025
This vulnerability resides in the Firefox browser's "Copy as cURL" feature which is designed to help developers and security researchers replicate HTTP requests by copying them in cURL command format. The flaw manifests when the feature fails to properly escape newline characters within request data, creating a potential vector for command injection attacks. When users copy such malformed commands and execute them in shell environments, the unescaped newlines can cause unintended command execution sequences. The vulnerability specifically impacts Firefox versions prior to 139, Firefox ESR versions prior to 115.24, and Firefox ESR versions prior to 128.11, indicating a widespread issue across multiple release channels and support cycles.
The technical implementation of this vulnerability falls under CWE-74, which describes improper neutralization of special elements used in a command, and CWE-155, which covers improper neutralization of special elements in data values. Attackers can exploit this by crafting malicious HTTP requests with embedded newline characters in headers or body data that get copied through the cURL feature. When these commands are pasted into terminal environments, the newlines break the command structure and can introduce additional commands that execute with the user's privileges. This represents a classic command injection vulnerability where user-controllable data is not properly sanitized before being executed in a shell context, making it particularly dangerous in environments where users may execute copied commands without proper verification.
The operational impact of this vulnerability extends beyond simple local code execution, as it leverages social engineering tactics to trick users into executing malicious commands through seemingly legitimate browser features. Attackers could craft phishing campaigns or manipulate web applications to generate malicious cURL commands that appear normal to users. The vulnerability's exploitation requires user interaction, as victims must actively copy and execute the commands, but this makes it particularly insidious in environments where users frequently work with command-line tools or are in development roles. The risk is heightened when users operate with elevated privileges or in automated environments where command execution occurs without explicit user confirmation.
Mitigation strategies should focus on both immediate remediation and defensive measures to protect against exploitation. Organizations must prioritize updating affected Firefox installations to versions 139 or later for regular releases, and to 115.24 or 128.11 for ESR versions, ensuring all systems receive the patched browser versions. Additionally, system administrators should implement security awareness training to educate users about the risks of executing copied commands without verification, particularly in development environments where such practices are common. Network-level protections should include monitoring for unusual command execution patterns and implementing shell command sanitization where possible. The ATT&CK framework categorizes this vulnerability under T1059.001 for command and scripting interpreter, highlighting the importance of controlling command execution through proper input validation and privilege separation. Organizations should also consider implementing application whitelisting policies that restrict execution of potentially dangerous commands from browser-based copy-paste operations, and deploy endpoint protection solutions that can detect and prevent malicious command injection attempts.