CVE-2021-47029

Kernel warning via unhandled monitor interface

Published Feb 28, 2024 · Updated May 11, 2026

Improper interface-type handling in Linux kernel 5.12 through 5.12.3 allows local users to trigger a kernel warning. mt76_connac_mcu_uni_add_dev sends a monitor interface through a connection-type switch that lacks a monitor case and invokes its default WARN_ON path. The path requires compatible mt76 Connac wireless hardware and permission to add and open a monitor interface; the published trace establishes a warning, not a crash.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper interface-type handling in Linux kernel 5.12 through 5.12.3 allows local users to trigger a kernel warning. mt76_connac_mcu_uni_add_dev sends a monitor interface through a connection-type switch that lacks a monitor case and invokes its default WARN_ON path. The path requires compatible mt76 Connac wireless hardware and permission to add and open a monitor interface; the published trace establishes a warning, not a crash.

The record

CVE
CVE-2021-47029
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-20
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.12
  2. Affected versionversion=d0e274af2f2e44b9d496f5d2c0431fdd2ea76fb8 <2554b9cb4b5e097c6071ec3ed5bc7c665c477ca7
  3. Affected versionversion=d0e274af2f2e44b9d496f5d2c0431fdd2ea76fb8 <c996f0346e40e3b1ac2ebaf0681df898fb157f60

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=d0e274af2f2e44b9d496f5d2c0431fdd2ea76fb8 <2554b9cb4b5e097c6071ec3ed5bc7c665c477ca7; version=d0e274af2f2e44b9d496f5d2c0431fdd2ea76fb8 <c996f0346e40e3b1ac2ebaf0681df898fb157f60

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.3SUSECVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo