Hazard

Is CVE-2021-31755 being exploited?

Weaponised and widely attempted

Reliable public exploit code exists, or mass exploitation attempts are probable. Patch inside days, not weeks.

Tenda AC11 Router Stack Buffer Overflow Vulnerability

Tenda · AC11 Router

CVSS 9.8 EPSS 86% no public exploit indexed Fix deadline passed 17 November 2021

What it is

Tenda AC11 devices contain a stack buffer overflow vulnerability in /goform/setmac which allows attackers to execute code via a crafted post request.

Why we say that

  • EPSS puts exploitation in the next 30 days at 86%
  • CISA's federal remediation deadline (2021-11-17) has passed
  • CVSS 9.8 critical
  • Listed in the CISA Known Exploited Vulnerabilities catalogue

Every line above comes from a named public source. Where the evidence is thin, we say so rather than inventing confidence — see methodology.

What to do

Apply updates per vendor instructions.

What it costs when this goes wrong

This is where UK enforcement meets the vulnerability record. Where an unfixed vulnerability leads to a breach, the ICO treats it as a security failure under UK GDPR. Recent cases:

All UK cases caused by unpatched software →