CVE-2024-26870

Kernel memory corruption via NFS xattr size underflow

Published Apr 17, 2024 · Updated Aug 5, 2026

Improper input validation in Linux NFSv4.2 allows local users to crash the kernel through a crafted listxattr call. nfs4_listxattr passes a zero remaining size to nfs4_listxattr_nfs4_user, causing a size_t underflow that drives an out-of-bounds heap copy. An existing NFSv4.2 mount and ordinary file access are required; hardened usercopy aborts with an oops, while unenforced builds expose kernel heap data and permit adjacent-object corruption.

CVSS severity7.8
High
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Linux NFSv4.2 allows local users to crash the kernel through a crafted listxattr call. nfs4_listxattr passes a zero remaining size to nfs4_listxattr_nfs4_user, causing a size_t underflow that drives an out-of-bounds heap copy. An existing NFSv4.2 mount and ordinary file access are required; hardened usercopy aborts with an oops, while unenforced builds expose kernel heap data and permit adjacent-object corruption.

The record

CVE
CVE-2024-26870
Published
Apr 17, 2024
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classifications
CWE-20, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 17, 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=0 <*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=012a211abd5db098094ce429de5f046368391e68 <06e828b3f1b206de08ef520fc46a40b22e1869cb; version=012a211abd5db098094ce429de5f046368391e68 <23bfecb4d852751d5e403557dd500bb563313baf; version=012a211abd5db098094ce429de5f046368391e68 <251a658bbfceafb4d58c76b77682c8bf7bcfad65; version=012a211abd5db098094ce429de5f046368391e68 <4403438eaca6e91f02d272211c4d6b045092396b; version=012a211abd5db098094ce429de5f046368391e68 <79cdcc765969d23f4e3d6ea115660c3333498768; version=012a211abd5db098094ce429de5f046368391e68 <80365c9f96015bbf048fdd6c8705d3f8770132bf; version=012a211abd5db098094ce429de5f046368391e68 <9d52865ff28245fc2134da9f99baff603a24407a; version=5.9

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8Linux kernel CVE teamCVSS: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

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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-20Improper Input Validation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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