CVE-2026-10189: Tenda W12 Stack Overflow RCE – Patch Guidance

Technical summary

The vulnerability resides in the cgiSysTimeInfoSet function within /bin/httpd on Tenda W12 3.0.0.7(4763). Insufficient bounds checking on the 'sec' argument permits a stack-based buffer overflow (CWE-119, CWE-121). An attacker with valid credentials can craft a malicious HTTP request to overflow the stack and potentially achieve remote code execution. The attack requires network access and valid authentication but no user interaction.

Business impact

Compromise of a Tenda W12 access point could grant an attacker persistent network presence, enable lateral movement into connected systems, or facilitate man-in-the-middle attacks. For organizations relying on these devices as network edge or branch office infrastructure, successful exploitation could disrupt connectivity, compromise data confidentiality, and enable further intrusion. The availability of public exploits significantly shortens the window before opportunistic attacks occur.

Affected systems

Tenda W12 firmware version 3.0.0.7(4763) is confirmed affected. Organizations should inventory deployments of this specific firmware build. Verify whether other W12 firmware versions or related Tenda products contain the same code path; check Tenda's advisory for the full list of affected versions and device models.

Exploitability

The vulnerability is exploitable remotely by any user with valid authentication credentials. No special tools are required beyond HTTP manipulation. Publicly disclosed exploit code is available, removing the barrier to weaponization. Attack complexity is low; the overflow is triggered by a simple parameter manipulation. However, the requirement for prior authentication limits exposure to insider threats or compromised user accounts rather than unauthenticated internet-wide scanning.

Remediation

Contact Tenda for a firmware update addressing this vulnerability. Immediately apply patches when available. As interim mitigation, restrict access to the web management interface to trusted administrative networks via firewall rules or network segmentation. Disable remote management features if not required. Monitor device logs for failed or successful authentication attempts followed by anomalous HTTP requests to the affected endpoint.

Patch guidance

Check Tenda's support website and security advisories for patched firmware versions. Verify the firmware release notes explicitly address CVE-2026-10189. Follow Tenda's documented firmware upgrade procedure carefully to avoid bricking the device. Test patches in a non-production environment first. Establish a firmware rollback plan in case the update causes network instability. Set a deadline for deployment across your asset inventory.

Detection guidance

Monitor HTTP traffic to /bin/httpd for requests to cgiSysTimeInfoSet with unusually large or malformed 'sec' parameters. Log all successful and failed authentication attempts on the device web interface. Enable verbose logging if available. Search historical logs for similar patterns. Configure intrusion detection signatures to flag buffer overflow patterns in HTTP POST data targeting this endpoint. Implement network access controls to permit management access only from designated administrative subnets.

Why prioritize this

This vulnerability merits urgent attention due to its HIGH CVSS score (8.8), network exploitability, complete impact potential (confidentiality, integrity, availability), and publicly available exploit code. While authentication is required, many organizations do not adequately segregate or rotate credentials for network device management, making compromise plausible. The combination of remote attack surface and code execution capability elevates risk substantially.

Risk score, explained

The CVSS 3.1 score of 8.8 reflects network-based attack vector, low attack complexity, and high impact across all three security pillars (CIA). The requirement for low-privilege authentication prevents a perfect 9.9 score. In practice, risk depends on credential hygiene, network segmentation, and the operational criticality of affected Tenda devices in your environment.

Frequently asked questions