CVE-2025-2767 is a remote code execution vulnerability classified under CWE-79 (Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting or XSS) affecting Arista NG Firewall version 17.1.1. The vulnerability arises from improper validation and sanitization of the User-Agent HTTP header, which is a common field sent by clients during HTTP requests. Specifically, the Arista NG Firewall fails to neutralize malicious scripts embedded within the User-Agent header before incorporating it into web page generation or internal processing. This flaw allows a remote attacker to inject arbitrary scripts that execute in the context of the firewall’s root user privileges. Exploitation requires minimal user interaction, meaning an attacker can craft malicious HTTP requests with a specially crafted User-Agent string to trigger the vulnerability without needing the victim to perform complex actions. Successful exploitation could lead to full system compromise, allowing the attacker to execute arbitrary code with root-level access on the firewall device. This could enable attackers to manipulate firewall rules, intercept or redirect network traffic, disable security controls, or use the compromised firewall as a foothold for further attacks within the network. Although no public exploits have been reported in the wild yet, the severity of the vulnerability is significant due to the high privileges gained and the critical role of NG Firewall devices in network security infrastructure. The vulnerability was identified and assigned by the Zero Day Initiative (ZDI) as ZDI-CAN-24407 and was published on April 23, 2025. No official patches have been released at the time of this analysis, increasing the urgency for mitigation.

For European organizations, the impact of this vulnerability is substantial. Arista NG Firewall is deployed in various enterprise and service provider environments across Europe, often protecting critical infrastructure and sensitive data. A successful attack could lead to unauthorized access to internal networks, data breaches, disruption of network services, and potential lateral movement by attackers within corporate or governmental networks. The root-level code execution capability means attackers can disable or alter firewall configurations, effectively bypassing security controls and exposing networks to further compromise. This risk is particularly acute for sectors such as finance, telecommunications, energy, and government agencies, where network security devices like NG Firewall are integral to operational continuity and data protection. Additionally, the minimal user interaction required lowers the barrier for exploitation, increasing the likelihood of targeted or opportunistic attacks. The absence of known exploits in the wild currently provides a window for proactive defense, but organizations should not delay remediation efforts given the critical nature of the vulnerability.

1. Immediate deployment of any available vendor updates or patches once released by Arista is critical. Monitor Arista’s official channels for patch announcements. 2. In the absence of patches, implement strict input validation and filtering at network ingress points to detect and block suspicious User-Agent headers containing script payloads. This can be done via web application firewalls (WAFs) or intrusion prevention systems (IPS) configured with custom rules targeting anomalous User-Agent strings. 3. Restrict administrative access to the NG Firewall management interface to trusted IP addresses and enforce multi-factor authentication to reduce the risk of exploitation via compromised credentials. 4. Conduct thorough logging and monitoring of HTTP headers and firewall management activities to detect unusual patterns indicative of exploitation attempts. 5. Segment the network to isolate critical firewall management interfaces from general user traffic, limiting exposure to remote attackers. 6. Educate security teams about this vulnerability to ensure rapid detection and response to any suspicious activity related to User-Agent header anomalies. 7. Consider deploying additional endpoint and network detection tools capable of identifying exploitation attempts targeting XSS vulnerabilities in network devices.