CVE-2024-56640

Kernel crash via unlocked SMC connection cleanup

Published Dec 27, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux kernel SMC networking code allows local users to crash the kernel by racing server-side connection cleanup. The smc_listen_work path can call smc_conn_free without the socket lock while another connection operation performs the same cleanup, repeatedly decrementing LGR and link reference counts until freed resources remain reachable. Exploitation requires low-privileged local access and an SMC server-side race; the observed consequence is a kernel warning or panic that interrupts the host.

CVSS severity7.8
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Use-after-free in the Linux kernel SMC networking code allows local users to crash the kernel by racing server-side connection cleanup. The smc_listen_work path can call smc_conn_free without the socket lock while another connection operation performs the same cleanup, repeatedly decrementing LGR and link reference counts until freed resources remain reachable. Exploitation requires low-privileged local access and an SMC server-side race; the observed consequence is a kernel warning or panic that interrupts the host.

The record

CVE
CVE-2024-56640
Published
Dec 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 27, 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=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <0cf598548a6c36d90681d53c6b77d52363f2f295
  2. Affected versionversion=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7
  3. Affected versionversion=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <673d606683ac70bc074ca6676b938bff18635226
  4. Affected versionversion=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <6f0ae06a234a78ae137064f2c89135ac078a00eb
  5. Affected versionversion=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <f502a88fdd415647a1f2dc45fac71b9c522a052b
  6. Affected versionversion=4.18

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <0cf598548a6c36d90681d53c6b77d52363f2f295; version=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <2c7f14ed9c19ec0f149479d1c2842ec1f9bf76d7; version=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <673d606683ac70bc074ca6676b938bff18635226; version=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <6f0ae06a234a78ae137064f2c89135ac078a00eb; version=3b2dec2603d5b06ad3af71c1164ca0b92df3d2a8 <f502a88fdd415647a1f2dc45fac71b9c522a052b; version=4.18

Published CVSS scores

7.8UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8CISA ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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-416Use After 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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