CVE intelligence and bounded remediation

CVE-2020-13391 — Tendacn Ac6 Firmware security vulnerability

Critical CVSS 9.8

An issue was discovered on Tenda AC6 V1.0 V15.03.05.19_multi_TD01, AC9 V1.0 V15.03.05.19(6318)_CN, AC9 V3.0 V15.03.06.42_multi, AC15 V1.0 V15.03.05.19_multi_TD01, and AC18 V15.03.05.19(6318_)_CN devices. There is a buffer overflow vulnerability in the router's web server -- httpd. While processing the /goform/SetSpeedWan speed_dir parameter for a POST request, a value is directly used in a sprintf to a local variable placed on the stack, which overwrites the return address of a function. An attacker can construct a payload to carry out arbitrary code execution attacks.

Severity
Critical
CVSS
9.8 (3.1)
Published
2020-05-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-120

Affected products

  • tendacn / ac6_firmware / v15.03.05.19_multi_td01
  • tendacn / ac9_firmware / v15.03.05.19(6318)
  • tendacn / ac15_firmware / v15.03.05.19_multi_td01
  • tendacn / ac18_firmware / v15.03.05.19(6318)
  • tendacn / ac9_firmware / v15.03.06.42_multi

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

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