CVE-2026-5549 Overview
A critical cryptographic vulnerability has been identified in the Tenda AC10 router firmware version 16.03.10.10_multi_TDE01. The vulnerability involves an exposed RSA 2048-bit private key stored in the file /webroot_ro/pem/privkeySrv.pem within the RSA 2048-bit Private Key Handler component. This hard-coded cryptographic key can be accessed remotely, potentially allowing attackers to decrypt encrypted communications, impersonate the device, or conduct man-in-the-middle attacks against users connected to affected routers.
Critical Impact
Remote attackers can exploit the exposed hard-coded RSA private key to compromise the confidentiality of encrypted communications and potentially impersonate the affected Tenda AC10 router.
Affected Products
- Tenda AC10 16.03.10.10_multi_TDE01
- Tenda AC10 routers running affected firmware versions
- Network environments utilizing affected Tenda AC10 devices
Discovery Timeline
- April 5, 2026 - CVE-2026-5549 published to NVD
- April 7, 2026 - Last updated in NVD database
Technical Details for CVE-2026-5549
Vulnerability Analysis
This vulnerability falls under CWE-320 (Key Management Errors) and represents a significant cryptographic weakness in embedded device security. The Tenda AC10 router contains a hard-coded RSA 2048-bit private key that is stored in a predictable location within the device's filesystem. The private key file located at /webroot_ro/pem/privkeySrv.pem can be accessed by remote attackers, completely undermining the cryptographic protections the key was intended to provide.
Hard-coded cryptographic keys in embedded devices are particularly dangerous because they cannot be changed by end users and are shared across all devices of the same model running the affected firmware. This means that once the key is extracted from a single device, it can be used to attack any other device running the same firmware version.
Root Cause
The root cause of this vulnerability is the inclusion of a static, hard-coded RSA private key within the device firmware. Rather than generating unique cryptographic keys during device initialization or first boot, the manufacturer embedded a shared private key that is identical across all devices running this firmware version. This approach violates fundamental cryptographic security principles that require private keys to remain secret and unique to each deployment.
Attack Vector
The attack can be launched remotely over the network. An attacker with network access to the device's web interface can potentially retrieve the exposed private key file. Once obtained, the private key enables several attack scenarios:
The attacker can decrypt any communications that were encrypted using the corresponding public key. This includes TLS/SSL sessions if the key is used for HTTPS administration interfaces. Additionally, the attacker can forge digital signatures, impersonate the device to connected clients, or conduct sophisticated man-in-the-middle attacks. Since the exploit has been publicly disclosed, the barrier to exploitation is significantly lowered.
For detailed technical analysis and proof of concept, refer to the GitHub Vulnerability Findings repository.
Detection Methods for CVE-2026-5549
Indicators of Compromise
- Unusual access attempts to /webroot_ro/pem/privkeySrv.pem or related certificate files in router logs
- Unexpected TLS certificate warnings when accessing the router's management interface
- Signs of man-in-the-middle attacks on traffic passing through the affected router
- Anomalous encrypted traffic patterns that suggest key compromise
Detection Strategies
- Monitor network traffic for attempts to access known vulnerable file paths on Tenda AC10 devices
- Implement network-based intrusion detection rules to identify exploitation attempts targeting the private key file
- Audit firmware versions across all Tenda AC10 devices in your environment to identify vulnerable installations
- Deploy endpoint detection solutions capable of identifying exploitation of embedded device vulnerabilities
Monitoring Recommendations
- Enable comprehensive logging on network segments containing Tenda AC10 routers
- Implement alerting for any direct file access attempts to the router's web root directories
- Regularly review TLS certificate fingerprints for affected devices to detect potential impersonation
- Monitor for unusual traffic patterns that may indicate active exploitation or man-in-the-middle attacks
How to Mitigate CVE-2026-5549
Immediate Actions Required
- Identify all Tenda AC10 routers running firmware version 16.03.10.10_multi_TDE01 in your environment
- Isolate affected devices from sensitive network segments until patched firmware is available
- Disable remote administration interfaces if not strictly required for operations
- Consider replacing affected devices with alternative hardware if vendor remediation is not forthcoming
Patch Information
At the time of publication, no official patch has been released by Tenda. Administrators should monitor the Tenda Official Website for firmware updates addressing this vulnerability. Additional technical details and community findings are available through VulDB #355313.
Workarounds
- Restrict network access to the router's management interface using firewall rules or network segmentation
- Place affected devices behind additional network security controls such as VPNs or jump hosts
- Disable HTTPS administration and use alternative secure management methods if available
- Consider device replacement if the router is deployed in a security-sensitive environment
# Example firewall rule to restrict management access
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
# Only allow management from trusted admin workstation
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.100 -j ACCEPT
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
