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New CVE Detected

CVE-2026-38577 – Hardcoded Credentials Leading to Root Access – Tenda HG21 V4.0.0-260302

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Summary

CVE-2026-38577 is a critical vulnerability (CWE-798: Use of Hard-coded Credentials) affecting the Tenda HG21 router running firmware V4.0.0-260302. The Admin account on affected devices uses insecure hardcoded credentials, allowing an unauthenticated remote attacker to gain root-level access to the device. The flaw carries a CVSS v3.1 base score of 9.8 (Critical).

Technical details

  • Root cause: The Admin account on affected firmware relies on hardcoded (embedded, non-configurable) credentials rather than credentials set or rotated by the device owner.
  • Trigger conditions: No prior authentication or user interaction is required; an attacker only needs network access to the device’s management interface.
  • Attack vector: Network (remote), with low attack complexity and no privileges required.
  • Impact: Successful exploitation grants root access to the device, resulting in complete loss of confidentiality, integrity, and availability of the device and any traffic/network it controls.

Affected software

  • Tenda HG21, firmware version V4.0.0-260302

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate: No official Tenda patch or advisory has been identified for this CVE at the time of writing. Check the Tenda support site for a firmware update superseding V4.0.0-260302 and apply it as soon as it is available.
  • If no patch is available:
    • Remove the device’s administrative/management interface from direct internet exposure; restrict access to trusted internal networks or VPN only.
    • Place the device behind a firewall that blocks inbound access to management ports/services from the WAN.
    • Monitor for unexpected administrative logins or configuration changes.
    • Where feasible, replace or isolate affected devices until a vendor fix is confirmed.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Page title: Tenda Web Master
  • Raw response body: an anchor element with a brand class and title="Tenda"

References

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