CVE-2026-6059 Overview
CVE-2026-6059 is a cross-site scripting (XSS) vulnerability affecting NEC Aterm wireless routers. The flaw resides in the web management interface and allows arbitrary scripts to execute in the browser of a user accessing the interface. Exploitation requires adjacent network access and user interaction, limiting attack scope to attackers already positioned on the local network segment. The vulnerability is tracked under CWE-79: Improper Neutralization of Input During Web Page Generation.
Critical Impact
An adjacent network attacker can execute arbitrary JavaScript in an administrator's browser session, potentially leading to session hijacking, configuration tampering, or credential theft against the Aterm management interface.
Affected Products
- NEC Aterm wireless routers (specific models listed in the vendor advisory)
- Web management interface component
- Refer to NEC Security Advisory NV26-002 for the complete model list
Discovery Timeline
- 2026-05-25 - CVE-2026-6059 published to NVD
- 2026-05-26 - Last updated in NVD database
Technical Details for CVE-2026-6059
Vulnerability Analysis
The vulnerability stems from improper neutralization of user-supplied input rendered within the Aterm web management interface. When a victim with an authenticated session views a page containing attacker-injected content, the browser executes the script in the context of the management interface origin. Because the management UI typically holds administrative privileges, script execution can issue authenticated requests to change router configuration, exfiltrate credentials stored in the session, or redirect the administrator to attacker-controlled resources.
Exploitation is constrained to the adjacent network attack surface. An attacker must reside on the same Layer 2 segment, share a Wi-Fi network, or otherwise have logical adjacency to the Aterm device. User interaction is required, meaning the administrator must access a crafted URL or view attacker-controlled content via the management interface.
Root Cause
The root cause is missing or insufficient output encoding when parameters supplied to the web management interface are reflected in HTML responses. Input handlers in the embedded web server fail to sanitize HTML metacharacters such as <, >, and quote characters before placing them into the response body.
Attack Vector
The attack vector is AV:A (Adjacent Network) with UI:A (Active user interaction required). An attacker on the local network crafts a malicious link or page that triggers the reflected XSS payload. When a router administrator clicks the link while authenticated to the Aterm interface, the payload executes in the browser. The vulnerability impact is limited to integrity at low scope, consistent with reflected XSS affecting the management UI.
No verified proof-of-concept code is publicly available. See the NEC Security Advisory NV26-002 for vendor-supplied technical details.
Detection Methods for CVE-2026-6059
Indicators of Compromise
- Unexpected HTTP requests to the Aterm management interface containing HTML or JavaScript metacharacters in query parameters
- Browser console errors or unusual script execution when administrators load Aterm management pages
- Unauthorized configuration changes to router settings following administrator access to the web UI
Detection Strategies
- Inspect HTTP traffic to router management interfaces for query strings containing <script>, javascript:, onerror=, or encoded equivalents
- Monitor for outbound connections from administrator workstations to unfamiliar domains immediately after accessing the Aterm UI
- Review router audit logs for configuration modifications that do not correspond to legitimate administrative activity
Monitoring Recommendations
- Deploy network sensors capable of inspecting LAN-side HTTP traffic to embedded device management interfaces
- Alert on access to Aterm management URLs from clients other than designated administrative workstations
- Capture and retain browser telemetry from systems used to administer network infrastructure
How to Mitigate CVE-2026-6059
Immediate Actions Required
- Apply the firmware update referenced in NEC Security Advisory NV26-002 as soon as it is available for your model
- Restrict access to the Aterm web management interface to a dedicated administrative VLAN or trusted host
- Require administrators to log out of the management interface immediately after configuration changes
Patch Information
NEC has published security advisory NV26-002 describing affected models and remediation. Administrators should consult the advisory for firmware versions that address the XSS issue and follow the vendor's update procedure. No third-party patches are available.
Workarounds
- Disable remote management features and limit administrative access to wired connections where feasible
- Use a dedicated browser profile or isolated browser session exclusively for router administration
- Avoid clicking external links while authenticated to the Aterm management interface
- Segment guest and untrusted Wi-Fi networks from the management network to reduce adjacent-network exposure
# Configuration example: restrict management interface access at the network layer
# Example firewall rule (concept) - block management UI from untrusted subnets
iptables -A FORWARD -s 192.168.100.0/24 -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -s 192.168.100.0/24 -d 192.168.1.1 -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
