CVE-2026-31437

Local system crash via NULL retry callback

Published Apr 22, 2026 · Updated Apr 22, 2026

NULL pointer dereference in Linux Kernel 6.18.17 through 6.18.20 and 6.19.7 through 6.19.10 allows local users to crash the system. The retry path in netfs_unbuffered_write() calls stream->prepare_write() without a NULL check after a write subrequest is marked for retry. Exploitation requires a netfs-backed filesystem lacking that callback, such as 9P, plus a get_user_pages() EFAULT during the retried write; the documented consequence is availability loss.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux Kernel 6.18.17 through 6.18.20 and 6.19.7 through 6.19.10 allows local users to crash the system. The retry path in netfs_unbuffered_write() calls stream->prepare_write() without a NULL check after a write subrequest is marked for retry. Exploitation requires a netfs-backed filesystem lacking that callback, such as 9P, plus a get_user_pages() EFAULT during the retried write; the documented consequence is availability loss.

The record

CVE
CVE-2026-31437
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 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=0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0 <7a5482f5ce891decbf36f2e6fab1e9fc4a76a684
  2. Affected versionversion=6.18.17 <6.18.21
  3. Affected versionversion=6.19.7 <6.19.11
  4. Affected versionversion=72d08d2839649d1c5efbe375751f4473fa4486af <a4d1b4ba9754bac3efebd06f583a44a7af52c0ab
  5. Affected versionversion=a0b4c7a49137ed21279f354eb59f49ddae8dffc2 <e9075e420a1eb3b52c60f3b95893a55e77419ce8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0 <7a5482f5ce891decbf36f2e6fab1e9fc4a76a684; version=6.18.17 <6.18.21; version=6.19.7 <6.19.11; version=72d08d2839649d1c5efbe375751f4473fa4486af <a4d1b4ba9754bac3efebd06f583a44a7af52c0ab; version=a0b4c7a49137ed21279f354eb59f49ddae8dffc2 <e9075e420a1eb3b52c60f3b95893a55e77419ce8

Published CVSS scores

5.5NIST NVDCVSS: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 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-476NULL Pointer Dereference
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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