CVE-2021-3609Public exploit

Local root escalation via CAN BCM use-after-free

Published Mar 3, 2022 · Updated Aug 3, 2024

Use-after-free flaws in Linux Kernel 2.6.25 through 5.13-rc6 allow local users to execute arbitrary code with root privileges via CAN BCM sockets. bcm_release() frees struct bcm_sock and struct bcm_op while bcm_rx_handler() or its timeout handler can still use them, permitting heap-sprayed data to redirect kernel control flow. Exploitation requires local low-privileged access, CAN BCM socket operations, and winning a race; success can overwrite kernel data and grant root control.

CVSS severity7.0
High
EPSS probability0.43%
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 flaws in Linux Kernel 2.6.25 through 5.13-rc6 allow local users to execute arbitrary code with root privileges via CAN BCM sockets. bcm_release() frees struct bcm_sock and struct bcm_op while bcm_rx_handler() or its timeout handler can still use them, permitting heap-sprayed data to redirect kernel control flow. Exploitation requires local low-privileged access, CAN BCM socket operations, and winning a race; success can overwrite kernel data and grant root control.

The record

CVE
CVE-2021-3609
Published
Mar 3, 2022
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 3, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=Affects kernel v2.6.25 to v5.13-rc6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=Affects kernel v2.6.25 to v5.13-rc6

Published CVSS scores

7.0NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:H/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 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 exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1068Exploitation for Privilege Escalation

Public exploit references

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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