CVE-2021-47395

Local denial of service via oversized VHT fields

Published May 21, 2024 · Updated May 11, 2026

Denial of service in Linux 4.7 through 5.14.9 allows local users to trigger a kernel warning via crafted radiotap VHT fields. ieee80211_parse_tx_radiotap forwards injected VHT MCS and NSS values to ieee80211_rate_set_vht without first limiting them to supported maxima. Low-privileged local access and a path that injects radiotap metadata through mac80211 are required; published assessments report no confidentiality or integrity impact.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux 4.7 through 5.14.9 allows local users to trigger a kernel warning via crafted radiotap VHT fields. ieee80211_parse_tx_radiotap forwards injected VHT MCS and NSS values to ieee80211_rate_set_vht without first limiting them to supported maxima. Low-privileged local access and a path that injects radiotap metadata through mac80211 are required; published assessments report no confidentiality or integrity impact.

The record

CVE
CVE-2021-47395
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-20, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=4.7
  2. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <1282bb00835ff79d2d9c023055d514df5b4de260
  3. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <13cb6d826e0ac0d144b0d48191ff1a111d32f0c6
  4. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <76538c7b4df314bb937e44c5cb1782f37d47443c
  5. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <997ee230e4f5285cd98445c102d9033c7ec4814b
  6. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <ab85997465b972d39d9747fc16311fa5773374b2
  7. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <ce5f372f5f084ff51c285fc27b232f15a3d00f0b
  8. Affected versionversion=646e76bb5daf4ca38438c69ffb72cccb605f3466 <e5bb852aa2ad963074f0ad73030dbc20a30853e3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.7; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <1282bb00835ff79d2d9c023055d514df5b4de260; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <13cb6d826e0ac0d144b0d48191ff1a111d32f0c6; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <76538c7b4df314bb937e44c5cb1782f37d47443c; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <997ee230e4f5285cd98445c102d9033c7ec4814b; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <ab85997465b972d39d9747fc16311fa5773374b2; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <ce5f372f5f084ff51c285fc27b232f15a3d00f0b; version=646e76bb5daf4ca38438c69ffb72cccb605f3466 <e5bb852aa2ad963074f0ad73030dbc20a30853e3

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

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

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Your stack

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