CVE-2021-47669

Local privilege escalation via vxcan use-after-free

Published Apr 17, 2025 · Updated Aug 5, 2026

Use-after-free in Linux kernel vxcan allows local users to disclose heap data, corrupt kernel memory, or crash the system. The vxcan_xmit function reads cfd->len from skb-backed canfd_frame memory after netif_rx_ni transfers and consumes that buffer. Reaching the flaw requires sending a CAN frame through a virtual vxcan interface; users can create one with CAP_NET_ADMIN in a user and network namespace.

CVSS severity7.8
High
EPSS probability0.19%
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 Linux kernel vxcan allows local users to disclose heap data, corrupt kernel memory, or crash the system. The vxcan_xmit function reads cfd->len from skb-backed canfd_frame memory after netif_rx_ni transfers and consumes that buffer. Reaching the flaw requires sending a CAN frame through a virtual vxcan interface; users can create one with CAP_NET_ADMIN in a user and network namespace.

The record

CVE
CVE-2021-47669
Published
Apr 17, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 17, 2025CVE 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

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=4.12
  2. Affected versionversion=a8f820a380a2a06fc4fe1a54159067958f800929 <6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105
  3. Affected versionversion=a8f820a380a2a06fc4fe1a54159067958f800929 <75854cad5d80976f6ea0f0431f8cedd3bcc475cb
  4. Affected versionversion=a8f820a380a2a06fc4fe1a54159067958f800929 <9b820875a32a3443d67bfd368e93038354e98052
  5. Affected versionversion=a8f820a380a2a06fc4fe1a54159067958f800929 <a24476b37167816e6352ca1a2cf3769847774f70
  6. Affected versionversion=a8f820a380a2a06fc4fe1a54159067958f800929 <e771a874076115df8bff27d325edfd2340e4ec69

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.12; version=a8f820a380a2a06fc4fe1a54159067958f800929 <6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105; version=a8f820a380a2a06fc4fe1a54159067958f800929 <75854cad5d80976f6ea0f0431f8cedd3bcc475cb; version=a8f820a380a2a06fc4fe1a54159067958f800929 <9b820875a32a3443d67bfd368e93038354e98052; version=a8f820a380a2a06fc4fe1a54159067958f800929 <a24476b37167816e6352ca1a2cf3769847774f70; version=a8f820a380a2a06fc4fe1a54159067958f800929 <e771a874076115df8bff27d325edfd2340e4ec69

Published CVSS scores

7.8Linux kernel CNACVSS: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.

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

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-416Use After Free
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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