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Fencer Intel
high 7.8

CVE-2024-56638 json

netfilter: nft_inner: incorrect percpu area handling under softirq

published last yr. modified 6d ago also EUVD-2024-53286

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 6.6.66, 6.12.5, 6.13
  • linux Debian 14, Debian 13 6.12.5-1

debian advisories DEBIAN-CVE-2024-56638

  • linux Ubuntu 24.04 LTS 6.8.0-58.60
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1027.29
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1028.30
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1023.27
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1024.24
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1027.32
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1010.12
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1028.32

ubuntu advisories UBUNTU-CVE-2024-56638

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.3.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.3.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1

suse advisories SUSE-SU-2025:01967-1SUSE-SU-2025:01951-1SUSE-SU-2025:01919-1SUSE-SU-2025:20192-1SUSE-SU-2025:20270-1SUSE-SU-2025:20190-1

Is CVE-2024-56638 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-56638 updated cvss 4.7

kernel: netfilter: nft_inner: incorrect percpu area handling under softirq

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more
    affected: no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6d ago

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.