CVE-2026-25624: Arista NGFW Administrative XSS Vulnerability

Technical summary

CVE-2026-25624 is an administrative XSS vulnerability (CWE-79) in the Arista Edge Threat Management NGFW web user interface. The vulnerability stems from insufficient input validation and output encoding on user-supplied variables within the dashboard layout. Specifically, unvalidated parameters are echoed back to the rendering context without sanitization, allowing injection of arbitrary JavaScript that executes in the security context of the administrator's session. The attack vector is network-accessible, requires high privileges (administrative access), and relies on user interaction (clicking or viewing a crafted dashboard state).

Business impact

Compromise of the firewall's administrative interface could allow an attacker to alter security policies, disable threat protections, redirect traffic, exfiltrate logs, or lock legitimate administrators out of the system. In environments where the firewall is critical to network perimeter defense, this could result in unauthorized lateral movement into protected networks, data exfiltration, or sustained network compromise. The business impact scales with organizational reliance on the NGFW for security enforcement.

Affected systems

Arista Edge Threat Management Next Generation Firewall (NGFW) deployments are affected. The vulnerability is specific to the web-based administrative dashboard. Any organization running this product with exposed administrative interfaces or where untrusted administrators have access should assess their risk. The vulnerability does not affect command-line or API management interfaces; impact is limited to the web UI.

Exploitability

Exploitability is constrained by several factors: the attacker must already possess or be able to social-engineer valid administrative credentials, the victim must interact with a crafted dashboard state (reflected XSS) or visit a page containing the injected payload (stored XSS), and the attack occurs within a high-privilege context. While the network vector is accessible, the high privilege requirement and user interaction dependency significantly limit real-world exploitation risk. The lack of public exploit code and absence from the CISA Known Exploited Vulnerabilities list suggest this is not currently being weaponized.

Remediation

Apply the security patch released by Arista that addresses input validation and output encoding in the dashboard layout. Verify patch availability in the official Arista security advisory. Until patching is possible, implement network segmentation to restrict administrative access to the NGFW web interface to trusted management networks or jump hosts. Use Web Application Firewalls (WAF) or reverse proxies to filter suspicious characters in dashboard parameters. Enforce multi-factor authentication (MFA) for administrative accounts to reduce the risk of credential compromise.

Patch guidance

Check the Arista security advisories and product documentation for the specific patched version of the NGFW software. Deploy patches in a maintenance window after testing in a non-production environment to ensure compatibility with your deployment. Prioritize patching systems where the administrative interface is internet-accessible or accessible from untrusted networks. Document patch deployment to fulfill compliance and audit requirements.

Detection guidance

Monitor web server logs for the NGFW administrative interface for suspicious request parameters containing script tags, event handlers (onclick, onload), or encoded payloads. Look for requests with unusual characters or lengths in dashboard parameters. Implement logging of administrative actions and dashboard modifications. Search for client-side JavaScript errors or unexpected DOM manipulation in browser console logs of administrative sessions. Use intrusion detection systems to flag requests containing XSS payloads to the NGFW interface. Monitor for changes to firewall policies or administrative user accounts that coincide with suspicious web requests.

Why prioritize this

Although the CVSS score is MEDIUM (5.7), this vulnerability warrants prioritization in environments where the NGFW performs critical security functions. The attack requires high privilege and user interaction, which moderates the score, but successful exploitation compromises the entire firewall's security posture. Organizations heavily dependent on this firewall for network protection should patch promptly. Lower priority can be assigned to isolated or lab environments, but production deployments should address this within standard vulnerability patching cycles.

Risk score, explained

The CVSS 3.1 score of 5.7 reflects the following factors: the network attack vector (AV:N) accounts for accessibility without physical presence; low attack complexity (AC:L) indicates no special conditions are needed to exploit the vulnerability itself; high privilege requirement (PR:H) significantly reduces the score because only administrators can exploit or be targeted; user interaction required (UI:R) further reduces likelihood; limited impact scope (S:U) means the damage is confined to the vulnerable component; high confidentiality impact (C:H) from session hijacking; low integrity impact (I:L) from potential rule modification; and low availability impact (A:L) from possible denial of administrative functions. The score appropriately reflects a medium-risk vulnerability with built-in constraints.

Frequently asked questions