CVE-2026-36802: Tenda PW201A Buffer Overflow DoS Vulnerability

Technical summary

CVE-2026-36802 is a classic buffer overflow (CWE-120) in the SafeMacFilter function of Tenda PW201A v1.0.5. The vulnerability stems from insufficient bounds checking on the 'page' parameter during HTTP request processing. When a malformed request exceeds the allocated buffer, stack or heap memory is overwritten, leading to application crash and loss of device availability. The attack vector is network-based, requires no authentication or special privileges, and impacts the availability attribute of the device.

Business impact

Organizations deploying Tenda PW201A v1.0.5 units face intermittent network outages if exploited. A DoS attack could disrupt wireless connectivity for entire floors or branches, interrupting productivity and potentially affecting dependent services. Repeated attacks may suggest reconnaissance by a threat actor preparing for lateral movement or data exfiltration. While remote code execution is not confirmed, the underlying memory corruption creates risk for future variant exploitation.

Affected systems

Tenda PW201A version 1.0.5 is confirmed vulnerable. Organizations using this model should verify firmware versions against vendor advisories to determine full scope. Tenda has released updated firmware to address this issue; verify against the vendor advisory for specific patch version numbers and supported devices.

Exploitability

Exploitability is straightforward. The vulnerability requires only a network connection and no authentication, authentication, or user interaction. An attacker can craft and send a single HTTP request from anywhere on the internet to trigger the crash. Proof-of-concept code is likely to emerge post-disclosure, and automated scanning tools may soon detect vulnerable endpoints. CVSS score of 7.5 (HIGH) reflects the ease of exploitation offset by the impact scope limited to availability.

Remediation

Firmware patching is the primary remediation. Tenda has released updated firmware; verify the specific version number and deployment timeline against the vendor advisory. Until patching is completed, consider network segmentation to restrict direct internet access to wireless management interfaces, implement rate-limiting on HTTP requests to the device, and monitor device logs for abnormal access patterns. Additionally, disable the SafeMacFilter feature if not in use.

Patch guidance

1. Check your Tenda PW201A firmware version (navigate to device settings or management portal; verify against the Tenda advisory for the exact patched version number). 2. Download the latest firmware from Tenda's official support site. 3. Back up device configuration before upgrading. 4. Perform a staged rollout in non-critical areas first to ensure stability. 5. Verify successful upgrade and test wireless connectivity and filtering policies post-patch. 6. Document patch date and version for compliance records.

Detection guidance

Monitor for HTTP requests with unusually long or malformed 'page' parameters sent to Tenda device management interfaces (typically port 80 or 443). Network intrusion detection systems (IDS) should be configured to flag requests exceeding normal parameter length thresholds. Log access to SafeMacFilter function endpoints and correlate with device reboots or service interruptions. Endpoint detection and response (EDR) tools on administrative machines can alert on suspicious connections to vulnerable device IPs.

Why prioritize this

Although this is a denial-of-service vulnerability with no confirmed code execution, the HIGH CVSS score, lack of authentication requirement, and ease of remote exploitation make it a priority for patching. The risk of weaponized DoS attacks targeting enterprise wireless infrastructure is significant, and the underlying memory corruption could be a stepping stone for more severe variants. Organizations should prioritize patching within 30 days of advisory publication.

Risk score, explained

CVSS 7.5 (HIGH) reflects: Network attack vector (AV:N) and low complexity (AC:L) result in easy exploitation; no authentication required (PR:N) and no user interaction needed (UI:N) increase likelihood; impact is limited to availability (A:H), not confidentiality or integrity (C:N, I:N), preventing a CRITICAL rating. The score appropriately captures the real-world risk of widespread DoS disruption without overstating the damage scope.

Frequently asked questions