CVE-2026-43376Network attack vector

Remote kernel code execution via premature oplock free

Published May 8, 2026 · Updated May 8, 2026

Use-after-free in Linux Kernel ksmbd allows remote attackers to corrupt kernel memory through SMB oplock and lease operations. The oplock teardown path calls kfree() immediately after clearing oplock_info, while opinfo_get() and proc_show_files() still dereference the object inside RCU read-side critical sections without a grace period. A reachable guest or public ksmbd share with oplocks enabled and concurrent SMB requests are required; stale atomic and field accesses can disclose or modify kernel memory, execute code, or panic or hang the host.

CVSS severity9.8
Critical
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in Linux Kernel ksmbd allows remote attackers to corrupt kernel memory through SMB oplock and lease operations. The oplock teardown path calls kfree() immediately after clearing oplock_info, while opinfo_get() and proc_show_files() still dereference the object inside RCU read-side critical sections without a grace period. A reachable guest or public ksmbd share with oplocks enabled and concurrent SMB requests are required; stale atomic and field accesses can disclose or modify kernel memory, execute code, or panic or hang the host.

The record

CVE
CVE-2026-43376
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <1d6abf145615dbfe267ce3b0a271f95e3780e18e
  2. Affected versionversion=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <1dfd062caa165ec9d7ee0823087930f3ab8a6294
  3. Affected versionversion=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <ce8507ee82c888126d8e7565e27c016308d24cde
  4. Affected versionversion=296cb5457cc6f4a754c4ae29855f8a253d52bcc6 <302fef75512b2c8329a3f5efab1ae7ba2562387a
  5. Affected versionversion=6.15
  6. Affected versionversion=d54ab1520d43e95f9b2e22d7a05fc9614192e5a5 <08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c
  7. Affected versionversion=d73686367ad68534257cd88a36ca3c52cb8b81d8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <1d6abf145615dbfe267ce3b0a271f95e3780e18e; version=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <1dfd062caa165ec9d7ee0823087930f3ab8a6294; version=18b4fac5ef17f77fed9417d22210ceafd6525fc7 <ce8507ee82c888126d8e7565e27c016308d24cde; version=296cb5457cc6f4a754c4ae29855f8a253d52bcc6 <302fef75512b2c8329a3f5efab1ae7ba2562387a; version=6.15; version=d54ab1520d43e95f9b2e22d7a05fc9614192e5a5 <08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c; version=d73686367ad68534257cd88a36ca3c52cb8b81d8

Published CVSS scores

9.8LinuxCVSS: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.

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1190Exploit Public-Facing Application

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo