CVE-2021-47082

Local system crash via TUN teardown double-free

Published Mar 4, 2024 · Updated Aug 5, 2026

A double-free in the Linux kernel TUN/TAP driver allows local users to crash the system by triggering failed device registration. tun_free_netdev releases statistics and SELinux security allocations that the failed register_netdevice path has already released. Reachability requires local low-privileged access to the TUN/TAP device-registration path; the demonstrated consequence is kernel memory corruption and a system crash.

CVSS severity7.8
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A double-free in the Linux kernel TUN/TAP driver allows local users to crash the system by triggering failed device registration. tun_free_netdev releases statistics and SELinux security allocations that the failed register_netdevice path has already released. Reachability requires local low-privileged access to the TUN/TAP device-registration path; the demonstrated consequence is kernel memory corruption and a system crash.

The record

CVE
CVE-2021-47082
Published
Mar 4, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-415, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 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=3.10.16 <3.11
  2. Affected versionversion=3.11.5 <3.12
  3. Affected versionversion=3.12
  4. Affected versionversion=662ca437e714caaab855b12415d6ffd815985bc0 <0c0e566f0387490d16f166808c72e9c772027681
  5. Affected versionversion=662ca437e714caaab855b12415d6ffd815985bc0 <158b515f703e75e7d68289bf4d98c664e1d632df
  6. Affected versionversion=662ca437e714caaab855b12415d6ffd815985bc0 <3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5
  7. Affected versionversion=662ca437e714caaab855b12415d6ffd815985bc0 <8eb43d635950e27c29f1e9e49a23b31637f37757
  8. Affected versionversion=662ca437e714caaab855b12415d6ffd815985bc0 <a01a4e9f5dc93335c716fa4023b1901956e8c904
  9. Affected versionversion=6fc265f7a86d81e052508d03da555188f5882c3e
  10. Affected versionversion=a81a02460bdf054ca0c60c5aed29941f7134092d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.10.16 <3.11; version=3.11.5 <3.12; version=3.12; version=662ca437e714caaab855b12415d6ffd815985bc0 <0c0e566f0387490d16f166808c72e9c772027681; version=662ca437e714caaab855b12415d6ffd815985bc0 <158b515f703e75e7d68289bf4d98c664e1d632df; version=662ca437e714caaab855b12415d6ffd815985bc0 <3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5; version=662ca437e714caaab855b12415d6ffd815985bc0 <8eb43d635950e27c29f1e9e49a23b31637f37757; version=662ca437e714caaab855b12415d6ffd815985bc0 <a01a4e9f5dc93335c716fa4023b1901956e8c904; version=6fc265f7a86d81e052508d03da555188f5882c3e; version=a81a02460bdf054ca0c60c5aed29941f7134092d

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-415Double Free
T1499.004Application or System Exploitation

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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