CVE-2021-31627Public exploit

Service crash via unchecked WPS index parameter

Published Oct 29, 2021 · Updated Jul 9, 2026

Stack buffer overflow in Tenda AC9 V1.0 and V3.0 firmware allows adjacent-network attackers to crash the web service through a WPS request. The /goform/WifiWpsOOB handler passes the unbounded index parameter to sprintf, overwriting the stack and loading an invalid address into the program counter. The factory-enabled WPS component requires no privileges or user interaction; the proof of concept demonstrates a repeatable crash, while the CVE record additionally reports arbitrary code execution.

CVSS severity8.8
High
EPSS probability1.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in Tenda AC9 V1.0 and V3.0 firmware allows adjacent-network attackers to crash the web service through a WPS request. The /goform/WifiWpsOOB handler passes the unbounded index parameter to sprintf, overwriting the stack and loading an invalid address into the program counter. The factory-enabled WPS component requires no privileges or user interaction; the proof of concept demonstrates a repeatable crash, while the CVE record additionally reports arbitrary code execution.

The record

CVE
CVE-2021-31627
Published
Oct 29, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.8NIST NVDAV:A/AC:L/Au:N/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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