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critical 9.4

CVE-2026-63830 in the critical feed json

net: skmsg: preserve sg.copy across SG transforms

published 3mo ago modified 20d ago also EUVD-2026-45496

cvss
9.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

net: skmsg: preserve sg.copy across SG transforms

The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages.

Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache.

Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting.

Patch / fix

  • Linux Linux 5.10.261, 5.15.212, 6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3, 7.2
  • linux Debian 12 6.1.177-1
  • linux Debian 13 6.12.95-1
  • linux Debian 14 7.1.3-1

debian advisories DEBIAN-CVE-2026-63830

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79

ubuntu advisories UBUNTU-CVE-2026-63830

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-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.87.3
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.87.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.87.3
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.87.3
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.87.3

suse advisories SUSE-SU-2026:4940-1SUSE-SU-2026:4935-1SUSE-SU-2026:24473-1SUSE-SU-2026:24553-1SUSE-SU-2026:24422-1SUSE-SU-2026:24446-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.40.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.40.1

opensuse advisories openSUSE-SU-2026:22167-1openSUSE-SU-2026:11339-1

Is CVE-2026-63830 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.

Check with Fencer

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-2026-63830 updated cvss 8.3

kernel: net: skmsg: preserve sg.copy across SG transforms

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    under investigation
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    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
yes
Technical impact
total
Assessed
26d ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-269 Improper Privilege Management
  • CWE-863 Incorrect Authorization
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.