CVE-2021-31756

Name: CVE-2021-31756
Creator: NVD / NIST
Published: 2021-05-07T23:15:07.077+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.90%

Last modified Jun 17, 2026

CVE-2021-31756 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /gofrom/setwanType allows attackers to execute arbitrary code on the system via a crafted post request. EPSS estimates a 2.90% chance of exploitation in the next 30 days.

Description

An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /gofrom/setwanType allows attackers to execute arbitrary code on the system via a crafted post request. This occurs when input vector controlled by malicious attack get copied to the stack variable.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

2.90%

85.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Tenda	Ac11 Firmware	<= 02.03.01.104_cn

References

https://github.com/Yu3H0/IoT_CVE/tree/main/Tenda/CVE_1Exploit, Issue Tracking, Third Party Advisory
https://github.com/Yu3H0/IoT_CVE/tree/main/Tenda/CVE_1Exploit, Issue Tracking, Third Party Advisory

Timeline

Published: May 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31756?

How severe is CVE-2021-31756?

CVE-2021-31756 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31756?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31756?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST