CVE-2025-63834 Overview
CVE-2025-63834 is a stored cross-site scripting (XSS) vulnerability affecting the Tenda AC18 wireless router running firmware version 15.03.05.05_multi. The flaw resides in the ssid parameter of the wireless settings interface. Remote attackers who reach the router's management interface can inject persistent JavaScript payloads. The stored payload executes in the browser of any user who subsequently loads the router's homepage. The weakness maps to [CWE-79] Improper Neutralization of Input During Web Page Generation.
Critical Impact
Attackers can persist arbitrary JavaScript in the router configuration, hijack administrator sessions, and pivot to further network device compromise through the router's web interface.
Affected Products
- Tenda AC18 hardware appliance
- Tenda AC18 firmware version 15.03.05.05_multi
- Deployments exposing the router web management interface to untrusted users
Discovery Timeline
- 2025-11-10 - CVE-2025-63834 published to the National Vulnerability Database
- 2026-06-17 - Last updated in the NVD database
Technical Details for CVE-2025-63834
Vulnerability Analysis
The Tenda AC18 web management console accepts the ssid parameter through the wireless configuration endpoint without sanitizing HTML or JavaScript metacharacters. The router stores the supplied value in device configuration and later renders it on the administrative homepage. When the homepage template writes the SSID into the response without output encoding, the browser interprets injected <script> content as executable code.
Because the payload is stored on the device, exploitation persists across administrator sessions and browser reloads. The attacker requires authenticated access to the wireless settings, but the injected script executes in the context of any user, including higher-privileged administrators, who later visits the interface. This scope change enables session token theft, forced configuration modifications through cross-site request forgery chaining, and delivery of secondary payloads. See the GitHub PoC Repository for reproduction details.
Root Cause
The root cause is missing input validation and output encoding on the ssid field. The firmware treats user-supplied SSID data as trusted text and reflects it verbatim into HTML responses on the router homepage.
Attack Vector
Exploitation requires network reachability to the router's HTTP management interface and low-privileged credentials capable of modifying wireless settings. The attacker submits a crafted SSID value containing JavaScript, then waits for a legitimate user to load the homepage. User interaction is required for payload execution.
No verified proof-of-concept code is published beyond the referenced writeup. The vulnerability manifests when the stored SSID value is rendered inside the homepage HTML without escaping. Refer to the researcher's report for the exact request structure.
Detection Methods for CVE-2025-63834
Indicators of Compromise
- SSID values in router configuration containing HTML tags, <script> markers, or JavaScript event handlers such as onerror= or onload=
- Unexpected outbound requests from administrator browsers to attacker-controlled hosts immediately after visiting the router UI
- Modified router configuration or credentials following an administrator session with the management console
Detection Strategies
- Periodically export and inspect Tenda AC18 configuration backups for non-printable or markup characters in the SSID field
- Monitor HTTP POST requests to wireless configuration endpoints for payloads containing angle brackets, quotes, or javascript: schemes
- Deploy browser-side Content Security Policy reporting on management workstations to surface inline script execution from router pages
Monitoring Recommendations
- Log and alert on all authentication events against the router's administrative interface, particularly from unmanaged clients
- Correlate administrator browser telemetry with router access logs to identify script execution following a homepage visit
- Track configuration changes to wireless settings and flag SSID modifications that include non-standard characters
How to Mitigate CVE-2025-63834
Immediate Actions Required
- Restrict access to the Tenda AC18 web management interface to trusted management VLANs and disable WAN-side administration
- Rotate administrator credentials for the router and any accounts reused across network devices
- Audit the current SSID value on affected devices and reset it to a plain alphanumeric string
- Instruct administrators to access the router UI from a dedicated, hardened browser profile until a patched firmware is available
Patch Information
No vendor advisory or firmware fix from Tenda is referenced in the NVD entry for CVE-2025-63834 at the time of publication. Monitor the Tenda support portal for firmware updates addressing the SSID parameter handling in the wireless settings interface.
Workarounds
- Segment the router management interface behind a firewall rule that only permits access from designated administrator hosts
- Disable remote web management and require local, wired access for configuration changes
- Replace end-of-support Tenda AC18 units with a supported model if the vendor does not issue a fix
# Example firewall rule restricting router admin access to a single management host
iptables -A INPUT -p tcp --dport 80 -s 192.0.2.10 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.0.2.10 -j ACCEPT
iptables -A INPUT -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.
