CVE-2021-47419

Local kernel code execution via uncanceled taprio timer

Published May 21, 2024 · Updated Aug 5, 2026

Use-after-free in taprio scheduling in affected Linux kernel releases allows local users to execute kernel code via rtnetlink. taprio_destroy frees the qdisc without canceling its armed hrtimer when qdisc_create reaches an error path before reset, leaving advance_sched to run on reclaimed memory. A low-privileged account can reach the path through a user and network namespace granting CAP_NET_ADMIN; exploitation can elevate privileges or panic the host.

CVSS severity9.8
Critical
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 taprio scheduling in affected Linux kernel releases allows local users to execute kernel code via rtnetlink. taprio_destroy frees the qdisc without canceling its armed hrtimer when qdisc_create reaches an error path before reset, leaving advance_sched to run on reclaimed memory. A low-privileged account can reach the path through a user and network namespace granting CAP_NET_ADMIN; exploitation can elevate privileges or panic the host.

The record

CVE
CVE-2021-47419
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=44d4775ca51805b376a8db5b34f650434a08e556 <7a1c1af341041221b3acb9d7036cc2b43e0efa75
  2. Affected versionversion=44d4775ca51805b376a8db5b34f650434a08e556 <a56d447f196fa9973c568f54c0d76d5391c3b0c0
  3. Affected versionversion=5.10.5 <5.10.73
  4. Affected versionversion=5.11
  5. Affected versionversion=5.4.87 <5.4.153
  6. Affected versionversion=a969a632cbe7165d448a5528806ad120c2599397 <3ec73ffeef54596c32aff0e73fe60971b9c8b866
  7. Affected versionversion=c71c512f4a65267e6a18163f4df729c489a51035 <c951c08a5996365aecbc5f1a9bddec3905e1ddfc

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=44d4775ca51805b376a8db5b34f650434a08e556 <7a1c1af341041221b3acb9d7036cc2b43e0efa75; version=44d4775ca51805b376a8db5b34f650434a08e556 <a56d447f196fa9973c568f54c0d76d5391c3b0c0; version=5.10.5 <5.10.73; version=5.11; version=5.4.87 <5.4.153; version=a969a632cbe7165d448a5528806ad120c2599397 <3ec73ffeef54596c32aff0e73fe60971b9c8b866; version=c71c512f4a65267e6a18163f4df729c489a51035 <c951c08a5996365aecbc5f1a9bddec3905e1ddfc

Published CVSS scores

9.8Linux kernel security teamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5CISA ADPCVSS: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.

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

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

T1068Exploitation for Privilege Escalation

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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