CVE-2021-31755: listed in the CISA KEV catalog

CVE-2021-31755 · CVSS 9.8 CRITICAL · EPSS 86% · KEV 2021-11-03

An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /goform/setmac allows attackers to execute arbitrary code on the system via a crafted post request.

Is CVE-2021-31755 exploited?

• Listed in the CISA KEV catalog on 2021-11-03.
• Federal remediation due 2021-11-17.
• Past that date by 1732 days.
• EPSS puts exploitation in the next 30 days at 86%.
• Public exploit code: none found in monitored sources.
• Public detection rules exist.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

No patch identifier recorded here yet.

What PlainSec published about CVE-2021-31755

• Fake Updates Hide Espionage Inside Normal Trust (2026-07-24)

Primary sources

• NVD record
• CISA KEV catalog
• Nuclei template

What this record does not say

• No affected package data.
• No patch identifier.

KEV and EPSS are re-checked daily. Record last updated 2026-08-11.