CVE-2026-11493: Tenda AC15 Samba Weak Password Requirements Vulnerability

Technical summary

CVE-2026-11493 involves improper password policy configuration in the Samba component of Tenda AC15 firmware 15.03.05.19. The vulnerability stems from weak controls over the /etc_ro/smb.conf configuration file, allowing local network attackers to modify password requirements. The attack chain requires high complexity and direct network access, but does not require authentication or user interaction. The CVSS 3.1 score of 5.0 (MEDIUM severity) reflects limited impact scope and the requirement for adjacent network proximity.

Business impact

For organizations deploying Tenda AC15 routers as network appliances or file servers, this vulnerability reduces the effectiveness of password-based access controls. An attacker could lower password complexity thresholds, enabling brute-force attacks against Samba shares. The impact is contained to SMB/CIFS file-sharing functionality rather than system-wide compromise, but credentials obtained through weakened password policies could enable lateral movement within the network segment served by the affected device.

Affected systems

Tenda AC15 routers running firmware version 15.03.05.19 are confirmed affected. The vulnerability is specific to this firmware release; other Tenda AC15 versions and other Tenda router models should be verified separately against Tenda's advisory documentation. Systems that have disabled Samba or do not rely on the SMB protocol are not exposed to this particular threat.

Exploitability

Public exploits are available, but practical exploitation remains difficult. The attack requires local network access—an attacker must be on the same network segment as the Tenda device. Additionally, the high complexity rating reflects the technical knowledge needed to manipulate the Samba configuration file and successfully weaken password policies. While not requiring pre-authentication, the attack is not a simple plug-and-play exploit; it demands understanding of Samba configuration syntax and local network positioning.

Remediation

Organizations should update Tenda AC15 firmware to the latest stable release beyond version 15.03.05.19. Tenda should be consulted for the patched firmware version and availability. Until patching is possible, restrict local network access to the router using network segmentation, disable Samba if not required, or implement access controls limiting which devices can communicate with the router's SMB services.

Patch guidance

Check Tenda's official support page and product advisory for firmware versions released after 15.03.05.19 that address CVE-2026-11493. Verify the patched version is compatible with your AC15 deployment before upgrading. Firmware updates should be applied during maintenance windows, as they typically require a device reboot. Document the current firmware version before and after patching for compliance records.

Detection guidance

Monitor network traffic for unusual SMB protocol activity on the affected router, particularly commands that modify the smb.conf file or alter password policy settings. Check the router's configuration audit logs for unauthorized changes to Samba parameters. Network intrusion detection systems should flag attempts to access or modify /etc_ro/smb.conf via SMB or SSH. Baseline the current Samba configuration on deployed AC15 devices and alert on deviations.

Why prioritize this

While the CVSS score is MEDIUM (5.0) and exploitation is difficult, the public availability of working exploits and the potential for password-policy manipulation justify prioritized attention. The vulnerability is most urgent for organizations relying on Tenda AC15 routers in environments with untrusted or semi-trusted local networks. Enterprises with strict network segmentation or those not using Samba may defer action, but should still plan patching as part of regular firmware maintenance cycles.

Risk score, explained

The score of 5.0 reflects moderate risk due to limited attack scope (adjacent network only), high attack complexity, and limited impact (confidentiality, integrity, and availability affected but not comprehensively). The CVSS vector CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L indicates that while the attack is locally feasible without authentication, the high complexity and bounded scope prevent a higher rating. Public exploit availability elevates practical risk beyond the base score.

Frequently asked questions