CVE-2026-11493: Tenda AC15 Auth Bypass Vulnerability

CVE-2026-11493 Overview

CVE-2026-11493 is a weak password requirements vulnerability affecting the Tenda AC15 wireless router running firmware version 15.03.05.19. The flaw resides in an unknown function within the /etc_ro/smb.conf configuration file of the Samba component. An attacker on the local network can leverage the weak credential policy to compromise Samba-shared resources on the device. The vulnerability is classified under CWE-521 and requires adjacent network access with high attack complexity. Public disclosure of the exploit details has been released through VulDB.

Critical Impact
Adjacent network attackers can exploit weak Samba password policies on Tenda AC15 routers to gain unauthorized access to shared resources, with limited impact on confidentiality, integrity, and availability.

Affected Products

Tenda AC15 router firmware version 15.03.05.19
Samba component configured via /etc_ro/smb.conf
Devices exposing SMB services on the local network

Discovery Timeline

2026-06-08 - CVE-2026-11493 published to NVD
2026-06-08 - Last updated in NVD database

Technical Details for CVE-2026-11493

Vulnerability Analysis

The vulnerability stems from improper password policy enforcement in the Samba configuration shipped with Tenda AC15 firmware 15.03.05.19. The /etc_ro/smb.conf file defines authentication parameters for SMB file sharing services exposed by the router. Because the configuration does not enforce strong password requirements, attackers can guess or brute-force credentials more easily than expected.

The weakness is local-network only, meaning an attacker must already have access to the same broadcast domain or Wi-Fi network as the router. Attack complexity is rated high, indicating that successful exploitation depends on environmental conditions outside the attacker's direct control. The EPSS data places the likelihood of near-term exploitation at a low percentile.

Root Cause

The root cause is a configuration design flaw within the read-only Samba configuration template embedded in the firmware. The smb.conf file ships without enforcing minimum password length, complexity, or lockout thresholds, mapping directly to [CWE-521: Weak Password Requirements].

Attack Vector

The attack vector is Adjacent Network (AV:A). An attacker connected to the same local network as the AC15 must initiate authentication attempts against the exposed Samba service. Successful credential guessing yields access to whatever shared resources the Samba daemon serves. Public proof-of-concept material referenced by VulDB outlines the conditions required to reproduce the issue. Refer to the VulDB CVE-2026-11493 entry and the Notion Tenda AC15 Disclosure for technical reproduction details.

No verified exploit code is available; the vulnerability manifests through the static Samba configuration rather than a discrete code path.

Detection Methods for CVE-2026-11493

Indicators of Compromise

Repeated SMB authentication failures originating from a single LAN host targeting the router's Samba service
Successful SMB logons using accounts that were never provisioned by an administrator
Unexpected file access patterns against shares served from the Tenda AC15

Detection Strategies

Inspect router firmware to confirm the contents of /etc_ro/smb.conf and identify weak min password length or absent lockout settings
Monitor SMB traffic (TCP/445 and TCP/139) on internal network segments for anomalous authentication volume directed at consumer-grade routers
Correlate Wi-Fi association events with subsequent SMB authentication attempts to identify rogue clients probing the router

Monitoring Recommendations

Forward switch and wireless controller logs to a centralized analytics platform for adjacent-network anomaly detection
Alert on repeated NT_STATUS_LOGON_FAILURE responses or equivalent SMB error codes from embedded devices
Periodically scan the LAN for unexpected SMB services exposed by network appliances

How to Mitigate CVE-2026-11493

Immediate Actions Required

Disable the Samba file sharing feature on the Tenda AC15 if it is not required for business operations
Restrict Wi-Fi access to trusted clients using WPA2/WPA3 with strong pre-shared keys to reduce adjacent network exposure
Replace any default or weak Samba credentials on the device with long, complex passphrases

Patch Information

At the time of publication, no vendor patch has been linked in the NVD record for CVE-2026-11493. Monitor the Tenda Official Website for firmware updates addressing the Samba configuration weakness on the AC15 platform.

Workarounds

Segment the AC15 onto an isolated VLAN with no untrusted client access until a firmware fix is released
Block inbound TCP/139 and TCP/445 to the router from untrusted LAN segments using upstream firewall rules
Where feasible, replace the affected device with hardware that enforces modern SMB authentication policies

bash

# Example: block SMB access to the router from untrusted hosts on an upstream Linux gateway
iptables -A FORWARD -p tcp -d <ac15_ip> --dport 445 -j DROP
iptables -A FORWARD -p tcp -d <ac15_ip> --dport 139 -j DROP