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Linux KernelOperating system · Linux

CVE-2026-43379

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-08
Fix available
A fix is available. Upgrade to 6.6.130 / 6.12.78 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Use-after-free vulnerability in ksmbd's smb_lazy_parent_lease_break_close() function where the opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is accessed after rcu_read_unlock() is called. A concurrent writer can free the memory between the unlock and subsequent dereferences to opinfo->is_lease, causing a use-after-free with CVSS 9.8.

MitigationThis kernel-level vulnerability requires a code patch to move the opinfo accesses inside the RCU read critical section or implement proper reference counting before the RCU lock is released.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.6.32, < 6.6.130>= 6.9, < 6.12.78>= 6.13, < 6.18.19>= 6.19, < 6.19.9= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel version
    Run 'uname -r' to get the running kernel version and compare it to the affected ranges: >= 6.6.32, < 6.6.130; >= 6.9, < 6.12.78; >= 6.13, < 6.18.19; >= 6.19, < 6.19.9; = 7.0
    Affected if Kernel version falls within any of the affected version ranges listed
  2. Verify ksmbd module is loaded
    Run 'lsmod | grep ksmbd' to check if the ksmbd kernel module is currently loaded
    Affected if ksmbd module is loaded and kernel version is in an affected range
  3. Check if ksmbd service is active
    Run 'systemctl status ksmbd' or check for running ksmbd processes with 'ps aux | grep ksmbd'
    Affected if ksmbd service is actively running and kernel version is in an affected range
  4. Inspect ksmbd configuration directory
    Check if /etc/ksmbd/ directory exists and contains configuration files, indicating ksmbd is configured on the system
    Affected if ksmbd is configured on the system and kernel version is in an affected range

The system is affected if the kernel version falls within any of the specified affected ranges AND ksmbd (the in-kernel SMB server) is loaded or actively running.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.130 / 6.12.78 / 6.18.19 or later
Fixed in 6.6.1306.12.786.18.19
Vendor patch git.kernel.org →
Interim mitigation

This kernel-level vulnerability requires a code patch to move the opinfo accesses inside the RCU read critical section or implement proper reference counting before the RCU lock is released.

Recommended fix High confidence

Upgrade to kernel version >= 6.6.130 (for 6.6.x), >= 6.12.78 (for 6.9-6.12.x), >= 6.18.19 (for 6.13-6.18.x), or >= 6.19.9 (for 6.19.x). Ideally move to the latest stable kernel release available for your distribution.

  1. 1. Identify your current Linux kernel version using 'uname -r'
  2. 2. Check which kernel version series you are running (e.g., 6.6.x, 6.9.x, 6.13.x, or 6.19.x)
  3. 3. Upgrade to a kernel version that includes the fix: for 6.6.x series upgrade to >= 6.6.130; for 6.9-6.12 series upgrade to >= 6.12.78; for 6.13-6.18 series upgrade to >= 6.18.19; for 6.19.x series upgrade to >= 6.19.9
  4. 4. On Debian/Ubuntu: 'sudo apt-get update && sudo apt-get upgrade linux-image-generic'
  5. 5. On RHEL/CentOS: 'sudo yum update kernel'
  6. 6. On Fedora: 'sudo dnf update kernel'
  7. 7. Reboot the system to load the new kernel: 'sudo reboot'
  8. 8. Verify the kernel has been upgraded: 'uname -r'
Caveat Kernel upgrades may require rebooting production systems; ensure compatibility with existing drivers and modules before upgrading in production environments.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,220
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43379 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data