dbcve.org
Linux KernelOperating system · Linux

CVE-2023-39191

HIGH · 8.2 CVSS v3.1 Published 2023-10-04
Fix available
A fix is available. Upgrade to 6.3 or later.
See remediation →
84/100
Remediation priority · High
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
An improper input validation flaw was found in the eBPF subsystem in the Linux kernel. The issue occurs due to a lack of proper validation of dynamic pointers within user-supplied eBPF programs prior to executing them. This may allow an attacker with CAP_BPF privileges to escalate privileges and execute arbitrary code in the context of the kernel.

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
How this class of weakness works · CWE-20

The application accepts input without confirming it is well-formed or within expected bounds, so malformed data can push the program into states its author never anticipated. Attackers probe these gaps to trigger crashes, bypass logic, or feed tainted values into more dangerous operations downstream. Remediating it well means validating and normalising every input at the boundary against a strict allow-list — not merely filtering known-bad values.

General guidance for the improper input validation class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 5.19, < 6.3
FedoraOperating system
Affected:= 38
Enterprise LinuxOperating system
Affected:= 9.0

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
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

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 6.3 or later
Fixed in 6.3
Vendor patch bugzilla.redhat.com →
Recommended fix High confidence

Linux Kernel 6.3 or later (or latest patched kernel version available from your distribution)

  1. For Fedora 38: Run 'sudo dnf update kernel' to update to the latest kernel version containing the security fix.
  2. Reboot the system to load the new kernel: 'sudo systemctl reboot'.
  3. Verify the running kernel version with 'uname -r' and confirm it is >= 6.3 or the latest patched version.
  4. For RHEL 9.0: Run 'sudo yum update kernel' or 'sudo dnf update kernel' to apply the security update.
  5. Reboot the system to load the patched kernel: 'sudo systemctl reboot'.
  6. Verify the running kernel version with 'uname -r' to confirm the fix is applied.
Caveat Kernel upgrades may require rebuilding third-party kernel modules; verify compatibility with the new kernel version before deployment in production environments.

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

Scan for this in your stack

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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-2023-39191 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