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Vulnerabilities

Vulnerability · CVE-2021-31755

Tenda AC11 Router Stack Buffer Overflow Vulnerability

Published May 7, 2021 · catalog updated Jun 16, 2026 · Tenda AC11 Router

Patch now

CVE-2021-31755 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Tenda AC11 Router against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
86.51%
Remediation
Remediation guidance
Affected products
cpe tenda/ac11 firmware · vendor Tenda AC11 Router

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe tenda/ac11 firmwareversion unspecified
  • vendor Tenda AC11 Routerversion unspecified

How to fix CVE-2021-31755

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-31755 is in the CISA known-exploited catalog, due Nov 17, 2021. Confirm Tenda AC11 Router against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply updates per vendor instructions.

What should an analyst verify?

CWE-787: Out-of-bounds Write. EPSS 86.51%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 7, 2021 · Catalog

    Detected

    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.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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

  • CISA KEVConfirmed exploitationCVE-2021-31755

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

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-31755

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-31755

    30-day exploitation probability 86.5%

    first.org
  • NIST NVDVulnerability recordCVE-2021-31755

    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.

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2021-31755

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

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.