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Linux KernelOperating system · Linux

CVE-2024-56638

HIGH · 7.8 CVSS v3.1 Published 2024-12-27
Fix available
A fix is available. Upgrade to 6.6.66 / 6.12.5 or later.
See remediation →
80/100
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
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_inner: incorrect percpu area handling under softirq Softirq can interrupt ongoing packet from process context that is walking over the percpu area that contains inner header offsets. Disable bh and perform three checks before restoring the percpu inner header offsets to validate that the percpu area is valid for this skbuff: 1) If the NFT_PKTINFO_INNER_FULL flag is set on, then this skbuff has already been parsed before for inner header fetching to register. 2) Validate that the percpu area refers to this skbuff using the skbuff pointer as a cookie. If there is a cookie mismatch, then this skbuff needs to be parsed again. 3) Finally, validate if the percpu area refers to this tunnel type. Only after these three checks the percpu area is restored to a on-stack copy and bh is enabled again. After inner header fetching, the on-stack copy is stored back to the percpu area.

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

A detailed technical summary for this CVE is being prepared.

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:>= 6.2, < 6.6.66>= 6.7, < 6.12.5= 6.13

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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 6.6.66 / 6.12.5 or later
Fixed in 6.6.666.12.5
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel 6.6.66 (or 6.12.5, or later 6.13.x stable release - whichever branch matches your current version)

  1. 1. Check the currently running kernel version using 'uname -r' or 'cat /proc/version'
  2. 2. Identify the appropriate fixed kernel version based on your distribution: for 6.6.x branch upgrade to >=6.6.66, for 6.7-6.12.x branch upgrade to >=6.12.5, for 6.13.x upgrade to a later stable release
  3. 3. Update the package repository and install the new kernel package using your distribution's package manager (e.g., 'apt-get update && apt-get install linux-image-<version>' for Debian/Ubuntu, 'yum update kernel' for RHEL/CentOS, or 'dnf update kernel' for Fedora)
  4. 4. Update bootloader configuration if necessary (grub2-mkconfig -o /boot/grub2/grub.cfg for RHEL/CentOS or update-grub for Debian/Ubuntu)
  5. 5. Reboot the system to load the fixed kernel
  6. 6. Verify the new kernel is running and the vulnerability is resolved by checking 'uname -r' matches the fixed version
Caveat Kernel upgrades may require rebuilding third-party kernel modules (like proprietary drivers) and should be tested in a staging environment before production deployment

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

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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-2024-56638 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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