CVE-2021-47519

Kernel memory exhaustion via leaked receive buffers

Published May 24, 2024 · Updated May 11, 2026

Memory leak in the M_CAN receive path in Linux 5.15 allows local users to exhaust kernel memory by provoking a FIFO read failure. The m_can_read_fifo function allocates an skb, but its second m_can_fifo_read error path returns without freeing that buffer. Repeated triggering requires an active M_CAN controller and a FIFO bus read error and can progressively reduce available kernel memory.

CVSS severity5.5
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Memory leak in the M_CAN receive path in Linux 5.15 allows local users to exhaust kernel memory by provoking a FIFO read failure. The m_can_read_fifo function allocates an skb, but its second m_can_fifo_read error path returns without freeing that buffer. Repeated triggering requires an active M_CAN controller and a FIFO bus read error and can progressively reduce available kernel memory.

The record

CVE
CVE-2021-47519
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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

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=5.15
  2. Affected versionversion=e39381770ec9ca3c51d8b9bd9cc6e01d78ea974a <31cb32a590d62b18f69a9a6d433f4e69c74fdd56
  3. Affected versionversion=e39381770ec9ca3c51d8b9bd9cc6e01d78ea974a <75a422165477dd12d2d20aa7c9ee7c9a281c9908

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=e39381770ec9ca3c51d8b9bd9cc6e01d78ea974a <31cb32a590d62b18f69a9a6d433f4e69c74fdd56; version=e39381770ec9ca3c51d8b9bd9cc6e01d78ea974a <75a422165477dd12d2d20aa7c9ee7c9a281c9908
The Linux Kernel Organization · Linux Kernelversion=5.15; version=e39381770ec9 <31cb32a590d6; version=e39381770ec9 <75a422165477

Published CVSS scores

3.3SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
7.5CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5NVDCVSS: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

CWE-401Missing Release of Memory after Effective Lifetime
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo