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Linux KernelOperating system · Linux

CVE-2023-6536

HIGH · 7.5 CVSS v3.1 Published 2024-02-07
Fix available
A fix is available. Upgrade to 5.4.268 / 5.10.209 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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
A flaw was found in the Linux kernel's NVMe driver. This issue may allow an unauthenticated malicious actor to send a set of crafted TCP packages when using NVMe over TCP, leading the NVMe driver to a NULL pointer dereference in the NVMe driver, causing kernel panic and a denial of service.

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

A NULL pointer dereference vulnerability exists in the Linux kernel's NVMe driver when using NVMe over TCP. An unauthenticated remote attacker can send crafted TCP packets to trigger the NULL pointer dereference, causing kernel panic and denial of service.

MitigationApply the Linux kernel security update/patch for this vulnerability. As a workaround, restrict access to NVMe over TCP ports and implement network segmentation to limit exposure to unauthenticated attackers.

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:>= 5.0, < 5.4.268>= 5.5, < 5.10.209>= 5.11, < 5.15.148>= 5.16, < 6.1.75>= 6.2, < 6.6.14>= 6.7, < 6.7.2
Codeready Linux Builder EusApplication
Affected:= 8.6= 9.2
Codeready Linux Builder Eus For Power Little Endian EusApplication
Affected:= 8.6_ppc64le= 9.2_ppc64le
Codeready Linux Builder For Arm64 EusApplication
Affected:= 8.6_aarch64= 9.2_aarch64
Codeready Linux Builder For Ibm Z Systems EusApplication
Affected:= 9.2_s390x
Enterprise LinuxOperating system
Affected:= 8.0= 9.0
Enterprise Linux EusOperating system
Affected:= 8.6= 9.2
Enterprise Linux For Arm 64 EusOperating system
Affected:= 8.6_aarch64= 9.2_aarch64

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 installed kernel version
    Run 'uname -r' or 'cat /proc/version' to get the kernel version
    Affected if The kernel version falls within any of these ranges: >=5.0 and <5.4.268, >=5.5 and <5.10.209, >=5.11 and <5.15.148, >=5.16 and <6.1.75, >=6.2 and <6.6.14, >=6.7 and <6.7.2
  2. Verify NVMe over TCP module availability
    Run 'lsmod | grep nvme' and 'modinfo nvme-tcp' to check if the nvme-tcp kernel module exists
    Affected if The nvme-tcp module is present on the system (vulnerability is present if kernel version is affected)
  3. Check for active NVMe over TCP connections
    Run 'nvme list' and inspect network connections on port 4420 (default NVMe-TCP port) using 'ss -tlnp | grep 4420' or 'netstat -tlnp | grep 4420'
    Affected if The system has NVMe over TCP connections or listeners configured and the kernel version is in the affected range

The environment is affected if the kernel version is within the vulnerable ranges AND the nvme-tcp module is available or NVMe over TCP is in use on the system.

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 5.4.268 / 5.10.209 / 5.15.148 or later
Fixed in 5.4.2685.10.2095.15.148
Interim mitigation

Apply the Linux kernel security update/patch for this vulnerability. As a workaround, restrict access to NVMe over TCP ports and implement network segmentation to limit exposure to unauthenticated attackers.

Recommended fix High confidence

Upgrade to kernel >= 5.4.268, >= 5.10.209, >= 5.15.148, or >= 6.1.75 (or latest available in your distribution's repository)

  1. 1. Identify the current running kernel version using 'uname -r'
  2. 2. Determine which kernel branch your current version belongs to (5.4.x, 5.10.x, 5.15.x, or 5.16+/6.x)
  3. 3. For RHEL/CentOS systems: run 'yum update kernel' or 'dnf update kernel' to install the latest available kernel that includes the security fix
  4. 4. For upstream kernels: upgrade to kernel version 5.4.268 or higher, 5.10.209 or higher, 5.15.148 or higher, or 6.1.75 or higher
  5. 5. After updating the kernel package, reboot the system to load the fixed kernel
  6. 6. Verify the running kernel is now a fixed version using 'uname -r'
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with proprietary kernel modules; test in staging environment first

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

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
Get the upgrade done

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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-2023-6536 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