CVE-2026-31444Network attack vector

Remote kernel crash via oplock publication race

Published Apr 22, 2026 · Updated Apr 22, 2026

Use-after-free and NULL dereference in Linux Kernel ksmbd allow remote attackers to crash the kernel through concurrent SMB lease handling. In smb_grant_oplock(), an allocation failure frees opinfo after opinfo_add() links it into ci->m_op_list, while another path publishes opinfo before assigning o_fp, exposing freed or NULL state to concurrent readers. Reachability requires an enabled ksmbd SMB server and concurrent oplock or lease handling; the bounded consequence is unsafe kernel memory access, including a NULL dereference and use-after-free.

CVSS severity9.8
Critical
EPSS probability0.45%
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 and NULL dereference in Linux Kernel ksmbd allow remote attackers to crash the kernel through concurrent SMB lease handling. In smb_grant_oplock(), an allocation failure frees opinfo after opinfo_add() links it into ci->m_op_list, while another path publishes opinfo before assigning o_fp, exposing freed or NULL state to concurrent readers. Reachability requires an enabled ksmbd SMB server and concurrent oplock or lease handling; the bounded consequence is unsafe kernel memory access, including a NULL dereference and use-after-free.

The record

CVE
CVE-2026-31444
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

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=08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c <7de55bba69cbf0f9280daaea385daf08bc076121
  2. Affected versionversion=1d6abf145615dbfe267ce3b0a271f95e3780e18e <a5c6f6d6ceefed2d5210ee420fb75f8362461f46
  3. Affected versionversion=1dfd062caa165ec9d7ee0823087930f3ab8a6294 <48623ec358c1c600fa1e38368746f933e0f1a617
  4. Affected versionversion=302fef75512b2c8329a3f5efab1ae7ba2562387a <9e785f004cbc56390479b77375726ea9b0d1a8a6
  5. Affected versionversion=6.12.78 <6.12.80
  6. Affected versionversion=6.18.19 <6.18.21
  7. Affected versionversion=6.19.9 <6.19.11
  8. Affected versionversion=6.6.130 <6.6.131
  9. Affected versionversion=ce8507ee82c888126d8e7565e27c016308d24cde <6d7e5a918c1d0aad06db0e17677b66fc9a471021

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c <7de55bba69cbf0f9280daaea385daf08bc076121; version=1d6abf145615dbfe267ce3b0a271f95e3780e18e <a5c6f6d6ceefed2d5210ee420fb75f8362461f46; version=1dfd062caa165ec9d7ee0823087930f3ab8a6294 <48623ec358c1c600fa1e38368746f933e0f1a617; version=302fef75512b2c8329a3f5efab1ae7ba2562387a <9e785f004cbc56390479b77375726ea9b0d1a8a6; version=6.12.78 <6.12.80; version=6.18.19 <6.18.21; version=6.19.9 <6.19.11; version=6.6.130 <6.6.131; version=ce8507ee82c888126d8e7565e27c016308d24cde <6d7e5a918c1d0aad06db0e17677b66fc9a471021

Published CVSS scores

9.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Endpoint Denial of Service: Application 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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