# CVE-2021-31755: Tenda AC11 Router Stack Buffer Overflow Vulnerability

Source: https://junglewise.ai/threats/cve-2021-31755-tenda-ac11-router-stack-buffer-overflow-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-31755 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

Tenda AC11 router devices are vulnerable to a stack-based buffer overflow in the /goform/setmac endpoint. An attacker can exploit this by sending a specially crafted POST request to execute arbitrary code on the system.

Vendors: [Tenda](https://junglewise.ai/threats/vendors/tenda).

## Quick answers

**Is CVE-2021-31755 exploited in the wild?** Yes. CVE-2021-31755 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-31755?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** Tenda AC11 through 02.03.01.104_CN.

**Is there a fix for CVE-2021-31755?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-31755 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2021-31755?** Check whether you run Tenda Ac11 Router. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Tenda AC11 through 02.03.01.104_CN

## Timeline

- 2021-05-07: disclosed: NVD Published Date
- 2021-11-03: kev added: Date added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-17: other: CISA KEV due date for remediation