CVE-2021-47611

Local service interruption via zero-length extended element

Published Jun 19, 2024 · Updated Aug 5, 2026

Improper validation in Linux kernel mac80211 before 5.16 allows local users to interrupt availability via a malformed extended element. The ieee80211_parse_extension_element function subtracts one from a zero data length and reads elem->data[0] without confirming that the extended-element ID byte exists. Low-privileged local access is required; the published impact is limited to availability, with no confidentiality or integrity effect.

CVSS severity5.5
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Linux kernel mac80211 before 5.16 allows local users to interrupt availability via a malformed extended element. The ieee80211_parse_extension_element function subtracts one from a zero data length and reads elem->data[0] without confirming that the extended-element ID byte exists. Low-privileged local access is required; the published impact is limited to availability, with no confidentiality or integrity effect.

The record

CVE
CVE-2021-47611
Published
Jun 19, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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?

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

  1. Affected versionversion=4.19
  2. Affected versionversion=41cbb0f5a29592874355e4159489eb08337cd50e <03029bb044ccee60adbc93e70713f3ae58abc3a1
  3. Affected versionversion=41cbb0f5a29592874355e4159489eb08337cd50e <768c0b19b50665e337c96858aa2b7928d6dcf756
  4. Affected versionversion=41cbb0f5a29592874355e4159489eb08337cd50e <7fd214fc7f2ee3a89f91e717e3cfad55f5a27045
  5. Affected versionversion=41cbb0f5a29592874355e4159489eb08337cd50e <a19cf6844b509d44ecbd536f33d314d91ecdd2b5
  6. Affected versionversion=41cbb0f5a29592874355e4159489eb08337cd50e <c62b16f98688ae7bc0ab23a6490481f4ce9b3a49

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.19; version=41cbb0f5a29592874355e4159489eb08337cd50e <03029bb044ccee60adbc93e70713f3ae58abc3a1; version=41cbb0f5a29592874355e4159489eb08337cd50e <768c0b19b50665e337c96858aa2b7928d6dcf756; version=41cbb0f5a29592874355e4159489eb08337cd50e <7fd214fc7f2ee3a89f91e717e3cfad55f5a27045; version=41cbb0f5a29592874355e4159489eb08337cd50e <a19cf6844b509d44ecbd536f33d314d91ecdd2b5; version=41cbb0f5a29592874355e4159489eb08337cd50e <c62b16f98688ae7bc0ab23a6490481f4ce9b3a49

Published CVSS scores

5.5NIST NVDCVSS: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

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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