← CVE catalog

CVE-2021-31755

Critical CVSS 9.8 Known exploited

Published 2021-05-07 · last changed 2026-06-17 · added to CISA KEV 2021-11-03

This one is being exploited in the wild.

CISA added CVE-2021-31755 to the Known Exploited Vulnerabilities catalog on 2021-11-03. Federal agencies are required to remediate it on a deadline. If you have affected machines, this is the class of finding that moves ahead of the rest of the queue.

The fix

We hold no Microsoft remediation data for CVE-2021-31755, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

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.

Sources

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H