CVE-2021-47299

Local system crash via XDP link race

Published May 21, 2024 · Updated May 11, 2026

Use-after-free in the Linux kernel XDP subsystem allows local users to crash the system by racing link attachment with device removal. Between dev_get_by_index() and dev_xdp_attach_link(), device unregistration can free the net_device while link->dev retains its address, so bpf_xdp_link_release() later dereferences freed memory. Triggering the race requires local low-privileged access and affects availability only, producing a kernel fault or panic rather than data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel XDP subsystem allows local users to crash the system by racing link attachment with device removal. Between dev_get_by_index() and dev_xdp_attach_link(), device unregistration can free the net_device while link->dev retains its address, so bpf_xdp_link_release() later dereferences freed memory. Triggering the race requires local low-privileged access and affects availability only, producing a kernel fault or panic rather than data disclosure or modification.

The record

CVE
CVE-2021-47299
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, 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

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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=5.9
  2. Affected versionversion=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <5acc7d3e8d342858405fbbc671221f676b547ce7
  3. Affected versionversion=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <a7537dc73e69ad9c0b67ad24ad3ebee954ed0af6
  4. Affected versionversion=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <ca9ba1de8f09976b45ccc8e655c51c6201992139

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.9; version=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <5acc7d3e8d342858405fbbc671221f676b547ce7; version=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <a7537dc73e69ad9c0b67ad24ad3ebee954ed0af6; version=aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 <ca9ba1de8f09976b45ccc8e655c51c6201992139

Published CVSS scores

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

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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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