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Authentication Bypass and RCE in Tenda AC Series Routers

CVE-2021-44971 is a critical authentication flaw reported in specific Tenda AC15 and AC5 firmware builds. Public research demonstrates protected data exposure and describes remote code execution as a possible chained impact, but safe automatic verification would require crossing the router's authentication boundary, so FixVibe does not scan for it.

CVE-2021-44971CWE-697

CVE-2021-44971 is an authentication-bypass vulnerability reported in specific firmware builds for Tenda AC-series routers [S1]. The public proof of concept demonstrates that a request without valid administrator credentials can reach protected management functionality on an affected device [S2].

Impact

A successful bypass can expose protected router and network configuration data [S1][S2]. The CVE record also describes remote code execution as a possible impact when the bypass is chained with a separate authenticated command-injection weakness [S1]. That chained impact is not the same as unauthenticated command execution being demonstrated by a normal web scan.

Evidence and affected products

The NVD record identifies these affected products [S1]:

  • Tenda AC15 V1.0 running firmware V15.03.05.20_multi
  • Tenda AC5 V1.0 running firmware V15.03.06.48_multi

The researcher's evidence demonstrates the authentication-control failure and protected-data exposure on the tested AC15 firmware [S2]. The cited public records do not establish that every Tenda AC-series device is affected, and they do not identify a confirmed fixed firmware release.

Why FixVibe will not check this automatically

A reliable positive result would require deliberately exercising the authentication bypass against protected router-management functionality and potentially receiving sensitive configuration data. FixVibe does not retrieve protected router configuration, collect device secrets, or attempt command execution. A passive model or firmware banner could suggest exposure, but it would not prove that the authentication control is vulnerable and could create misleading results.

This article therefore remains a research note rather than a live FixVibe scanner check.

Remediation

Owners of potentially affected devices should:

  • Inventory the exact router model and installed firmware from a trusted local administration session.
  • Obtain current firmware and model-specific guidance directly from Tenda support or an authorized support channel.
  • Disable internet-facing remote administration unless it is strictly required.
  • Restrict the management interface to a trusted local network or VPN and enforce upstream firewall controls.
  • Treat exposed management access as a potential incident: review settings, rotate router and Wi-Fi credentials, and investigate unexpected configuration changes.
Authentication Bypass and RCE in Tenda AC Series Routers — FixVibe research · FixVibe