CVE-2024-27020

Local kernel compromise via nf_tables expression race

Published May 1, 2024 · Updated Aug 5, 2026

Race condition in Linux kernel netfilter allows local users to compromise the kernel through concurrent expression-type queries. __nft_expr_type_get() traverses nf_tables_expressions without RCU protection while nft_unregister_expr() can remove and free the selected type. An unprivileged user can trigger both sides from separate user and network namespaces, enabling kernel disclosure, memory writes, control-flow hijacking, or a panic.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux kernel netfilter allows local users to compromise the kernel through concurrent expression-type queries. __nft_expr_type_get() traverses nf_tables_expressions without RCU protection while nft_unregister_expr() can remove and free the selected type. An unprivileged user can trigger both sides from separate user and network namespaces, enabling kernel disclosure, memory writes, control-flow hijacking, or a panic.

The record

CVE
CVE-2024-27020
Published
May 1, 2024
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-362, T1068, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 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=V3.1.0 <V3.1.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=3.13; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <01f1a678b05ade4b1248019c2dcca773aebbeb7f; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <0b6de00206adbbfc6373b3ae38d2a6f197987907; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <8d56bad42ac4c43c6c72ddd6a654a2628bf839c5; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <934e66e231cff2b18faa2c8aad0b8cec13957e05; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <939109c0a8e2a006a6cc8209e262d25065f4403a; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <a9ebf340d123ae12582210407f879d6a5a1bc25b; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <b38a133d37fa421c8447b383d788c9cc6f5cb34c; version=ef1f7df9170dbd875ce198ba84e6ab80f6fc139e <f969eb84ce482331a991079ab7a5c4dc3b7f89bf
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE XCM/XRM/XCH/XRH-300 familyversion=0 <V3.1
Siemens · RUGGEDCOM RST2428Pversion=0 <V3.1
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5

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
5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.0CISACVSS: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.

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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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1068Exploitation for Privilege Escalation
T1499Endpoint Denial of Service

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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