CVE-2026-2148 Overview
A security vulnerability has been identified in Tenda AC21 router firmware version 16.03.08.16. The vulnerability affects an unknown function within the /cgi-bin/DownloadFlash endpoint of the Web Management Interface component. Successful exploitation allows unauthorized information disclosure through remote network access. The exploit has been publicly disclosed and may be actively used in attacks.
Critical Impact
Unauthenticated attackers can remotely access sensitive device information through the Web Management Interface, potentially exposing configuration data, credentials, or other sensitive router information.
Affected Products
- Tenda AC21 Firmware version 16.03.08.16
- Tenda AC21 Hardware devices running affected firmware
Discovery Timeline
- 2026-02-08 - CVE-2026-2148 published to NVD
- 2026-02-10 - Last updated in NVD database
Technical Details for CVE-2026-2148
Vulnerability Analysis
This vulnerability is classified as an Information Disclosure issue (CWE-200) affecting the Tenda AC21 router's web management interface. The vulnerable component resides in the /cgi-bin/DownloadFlash endpoint, which fails to properly validate or restrict access to sensitive information.
The flaw can be exploited remotely over the network without requiring authentication or user interaction, making it particularly concerning for internet-exposed devices. While the vulnerability does not directly allow code execution or system compromise, the exposed information could facilitate further attacks against the device or network.
Root Cause
The root cause stems from improper access control mechanisms within the /cgi-bin/DownloadFlash handler. The endpoint appears to lack proper authentication checks or authorization validation, allowing unauthenticated users to request and retrieve sensitive data that should only be accessible to authenticated administrators.
This represents a failure to implement the principle of least privilege and proper access control boundaries around sensitive functionality in the router's web interface.
Attack Vector
The attack can be initiated remotely over the network by sending crafted HTTP requests to the vulnerable /cgi-bin/DownloadFlash endpoint on the device's web management interface. No authentication credentials or user interaction is required for successful exploitation.
Attackers can leverage this vulnerability to extract sensitive device configuration data, which may include network settings, credential information, or other data that could be used to further compromise the device or pivot to other systems on the network.
Technical details and proof-of-concept information have been publicly disclosed through the GitHub CVE Issue Discussion. Additional vulnerability tracking information is available at VulDB #344850.
Detection Methods for CVE-2026-2148
Indicators of Compromise
- Unexpected HTTP requests to /cgi-bin/DownloadFlash from external IP addresses
- Unusual access patterns to the router's web management interface
- Outbound data transfers from the router containing configuration or credential data
- Multiple failed or successful authentication attempts following information disclosure attempts
Detection Strategies
- Monitor network traffic for requests targeting /cgi-bin/DownloadFlash endpoints on Tenda AC21 devices
- Implement intrusion detection signatures to identify exploitation attempts against the vulnerable endpoint
- Review web server access logs for suspicious access patterns to CGI endpoints
- Deploy network monitoring to detect unauthorized data exfiltration from router devices
Monitoring Recommendations
- Enable and regularly review access logs on Tenda AC21 devices if supported
- Implement network-level monitoring for traffic to and from router management interfaces
- Configure alerts for access attempts to known vulnerable endpoints from untrusted sources
- Monitor for unusual configuration changes or access patterns on affected devices
How to Mitigate CVE-2026-2148
Immediate Actions Required
- Restrict access to the router's web management interface to trusted internal networks only
- Disable remote management features if not required for operations
- Implement firewall rules to block external access to the web management interface
- Segment the network to limit exposure of management interfaces to untrusted networks
Patch Information
At the time of publication, no vendor patch has been confirmed for this vulnerability. Users should monitor the Tenda Official Website for firmware updates addressing this security issue. Check for updates to Tenda AC21 firmware versions newer than 16.03.08.16 that may contain security fixes.
Workarounds
- Disable the web management interface if not required for device administration
- Configure access control lists (ACLs) to limit management interface access to specific trusted IP addresses
- Place the router behind a firewall that restricts access to administrative interfaces
- Consider replacing vulnerable devices with alternative solutions if patches are not made available
# Network firewall rule example to block external access to management interface
# Block external access to web management port (typically 80/443)
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
