Description

Buffer Overflow vulnerability in Tenda W20E V16.01.0.6(2782) allows an attacker to execute arbitrary code. This is an incomplete fix for CVE-2025-44867 and CVE-2026-36819

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-08-17T21:16:47.840Z",
  "pubdate": "2026-08-17T21:16:47.840Z",
  "executiveSummary": "A buffer overflow vulnerability exists in Tenda W20E V16.01.0.6(2782), stemming from an incomplete fix for previously identified vulnerabilities CVE-2025-44867 and CVE-2026-36819. This security flaw allows a remote or local attacker to exploit improper input handling within the affected firmware to overwrite memory buffers. Successful exploitation of this vulnerability can lead to arbitrary code execution, potentially compromising the confidentiality, integrity, and availability of the targeted routing device. The flaw affects Tenda W20E running firmware version V16.01.0.6(2782) and represents a significant risk as it permits attackers to bypass intended security controls and execute arbitrary machine instructions. The risk implications include full device compromise, potential pivoting into connected local area networks, and persistent denial of service conditions. Attacker capabilities involve crafting specialized payloads designed to manipulate vulnerable memory spaces during input processing. Given that this vulnerability represents an insufficient remediation of prior CVEs, it highlights a recurring flaw in the input validation mechanisms of the targeted firmware component.",
  "technicalDetails": "The vulnerability is a classic buffer overflow condition residing in the firmware of the Tenda W20E router, specifically affecting version V16.01.0.6(2782). The root cause of the flaw lies in the lack of adequate bounds checking and input sanitization when processing specific data parameters within the vulnerable component. Because previous remediation efforts associated with CVE-2025-44867 and CVE-2026-36819 failed to comprehensively secure all input vectors or internal parsing routines, memory corruption conditions can still be triggered by supplying overly large inputs that exceed the allocated stack or heap buffer size.\nDuring the attack flow, an adversary crafts a malicious payload containing shellcode and structural memory manipulation data, such as altered return addresses or function pointers. When the Tenda W20E firmware processes this input without verifying its length against the destination buffer boundaries, the excess data overflows into adjacent memory regions. This overwrites critical execution context data on the call stack or control structures in heap memory. As the vulnerable application or operating system routine continues execution, it attempts to return to or utilize the corrupted pointers, redirecting the execution flow to the attacker-supplied shellcode.\nThe payload behavior involves executing arbitrary code within the security context of the affected process, which typically operates with elevated privileges on embedded network devices. This grants the attacker deep access to the underlying operating system. Post-exploitation impact includes unauthorized administrative access, modification of system configurations, interception of network traffic transiting the router, and installation of persistent malware or backdoors. The vulnerability highlights systemic gaps in prior patch implementations for CVE-2025-44867 and CVE-2026-36819, indicating that thorough regression testing and comprehensive input validation routines are required to permanently resolve the underlying memory safety issues in the Tenda W20E firmware architecture."
}