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Fencer Vulns
high 7.8

CVE-2026-53366 json

ipv4: account for fraggap on the paged allocation path

published 2026-07-16 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-44868

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

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

ipv4: account for fraggap on the paged allocation path

In __ip_append_data(), when the paged-allocation branch is taken, alloclen and pagedlen are computed as

alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen;

datalen already includes fraggap, but the fraggap bytes carried over from the previous skb are copied into the new skb's linear area at offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount.

The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen.

After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic.

Patch / fix

  • Linux Linux 6.1.178, 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-2026-53366

  • linux Ubuntu 24.04 LTS 6.8.0-147.147
  • linux Ubuntu 26.04 LTS 7.0.0-31.31
  • 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 24.04 LTS 6.8.0-1071.79
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1011.11
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1066.74
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1006.7

ubuntu advisories UBUNTU-CVE-2026-53366

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 RHEL 9 5.14.0-687.46.1.el9_8
  • rv RHEL 9 5.14.0-687.46.1.el9_8
  • perf RHEL 9 5.14.0-687.46.1.el9_8
  • rtla RHEL 9 5.14.0-687.46.1.el9_8
  • libperf RHEL 9 5.14.0-687.46.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.46.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.46.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.46.1.el9_8

red hat advisories RHSA-2026:66180RHSA-2026:34911

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4254-1SUSE-SU-2026:4369-1SUSE-SU-2026:4120-1SUSE-SU-2026:23488-1SUSE-SU-2026:23536-1SUSE-SU-2026:23481-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1openSUSE-SU-2026:11339-1

  • kernel AlmaLinux 9 5.14.0-687.46.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.46.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.46.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.46.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.46.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.46.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.46.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.46.1.el9_8

almalinux advisories ALSA-2026:66180

  • kernel Rocky Linux 9 5.14.0-687.46.1.el9_8

rocky linux advisories RLSA-2026:66180

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-2026-53366 updated cvss 7.8

kernel: ipv4: account for fraggap on the paged allocation path

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.46.1.el9_8, perf 5.14.0-687.46.1.el9_8, rtla 5.14.0-687.46.1.el9_8, python3-perf 5.14.0-687.46.1.el9_8, kernel-devel-matched 5.14.0-687.46.1.el9_8, kernel-64k-devel-matched 5.14.0-687.46.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.30.1.el10_2, perf 6.12.0-211.30.1.el10_2, rtla 6.12.0-211.30.1.el10_2, python3-perf 6.12.0-211.30.1.el10_2, kernel-devel-matched 6.12.0-211.30.1.el10_2, kernel-64k-devel-matched 6.12.0-211.30.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:34911
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.86.1.el10_0, perf 6.12.0-55.86.1.el10_0, rtla 6.12.0-55.86.1.el10_0, python3-perf 6.12.0-55.86.1.el10_0, kernel-devel-matched 6.12.0-55.86.1.el10_0, kernel-64k-devel-matched 6.12.0-55.86.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:35840
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.46.1.el9_8, kernel-64k 5.14.0-687.46.1.el9_8, kernel-core 5.14.0-687.46.1.el9_8, kernel-tools 5.14.0-687.46.1.el9_8, kernel-modules 5.14.0-687.46.1.el9_8, kernel-64k-core 5.14.0-687.46.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.30.1.el10_2, kernel-64k 6.12.0-211.30.1.el10_2, kernel-core 6.12.0-211.30.1.el10_2, kernel-tools 6.12.0-211.30.1.el10_2, kernel-modules 6.12.0-211.30.1.el10_2, kernel-64k-core 6.12.0-211.30.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:34911
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.86.1.el10_0, kernel-64k 6.12.0-55.86.1.el10_0, kernel-core 6.12.0-55.86.1.el10_0, kernel-tools 6.12.0-55.86.1.el10_0, kernel-modules 6.12.0-55.86.1.el10_0, kernel-64k-core 6.12.0-55.86.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:35840
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.46.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.46.1.el9_8
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.30.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.30.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.30.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.30.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.30.1.el10_2
    fixed: vendor fix RHSA-2026:34911
show 8 more
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.86.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.86.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.86.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.86.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.86.1.el10_0
    fixed: vendor fix RHSA-2026:35840
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.46.1.el9_8, kernel-rt-64k 5.14.0-687.46.1.el9_8, kernel-rt-core 5.14.0-687.46.1.el9_8, kernel-rt-modules 5.14.0-687.46.1.el9_8, kernel-rt-64k-core 5.14.0-687.46.1.el9_8, kernel-rt-debug-core 5.14.0-687.46.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.30.1.el10_2, kernel-rt-64k 6.12.0-211.30.1.el10_2, kernel-rt-core 6.12.0-211.30.1.el10_2, kernel-rt-modules 6.12.0-211.30.1.el10_2, kernel-rt-64k-core 6.12.0-211.30.1.el10_2, kernel-rt-debug-core 6.12.0-211.30.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:34911
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.86.1.el10_0, kernel-rt-64k 6.12.0-55.86.1.el10_0, kernel-rt-core 6.12.0-55.86.1.el10_0, kernel-rt-modules 6.12.0-55.86.1.el10_0, kernel-rt-64k-core 6.12.0-55.86.1.el10_0, kernel-rt-debug-core 6.12.0-55.86.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:35840
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.46.1.el9_8, kernel-rt-core 5.14.0-687.46.1.el9_8, kernel-rt-modules 5.14.0-687.46.1.el9_8, kernel-rt-debug-core 5.14.0-687.46.1.el9_8, kernel-rt-modules-core 5.14.0-687.46.1.el9_8, kernel-rt-debug-modules 5.14.0-687.46.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:66180
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.30.1.el10_2, kernel-rt-core 6.12.0-211.30.1.el10_2, kernel-rt-modules 6.12.0-211.30.1.el10_2, kernel-rt-debug-core 6.12.0-211.30.1.el10_2, kernel-rt-modules-core 6.12.0-211.30.1.el10_2, kernel-rt-debug-modules 6.12.0-211.30.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:34911
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.86.1.el10_0, kernel-rt-kvm 6.12.0-55.86.1.el10_0, kernel-rt-core 6.12.0-55.86.1.el10_0, kernel-rt-modules 6.12.0-55.86.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.86.1.el10_0, kernel-rt-debug-core 6.12.0-55.86.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:35840
  • 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 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 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
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 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

Weakness
  • CWE-131 Incorrect Calculation of Buffer Size
Technology feeds

References

Sources

Fencer Vulns 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.