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Fencer Vulns
critical 9.8

CVE-2026-43186 in the critical feed json

ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()

published 2026-05-06 6 mo ago modified 2026-10-19 20 d ago also EUVD-2026-27747

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

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

ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()

On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic.

Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it:

- in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written.

Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00).

Patch / fix

  • Linux Linux 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0
  • linux Debian 12 6.1.170-1
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.19.6-1

debian advisories DEBIAN-CVE-2026-43186

  • linux Ubuntu 22.04 LTS 5.15.0-185.195
  • linux Ubuntu 24.04 LTS 6.8.0-134.134
  • linux Ubuntu 25.10 6.17.0-40.40
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1111.118
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1060.63
  • linux-aws Ubuntu 25.10 6.17.0-1019.19
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1111.121
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1063.69

ubuntu advisories UBUNTU-CVE-2026-43186

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 10.2 6.12.0-211.44.1.el10_2
  • rv RHEL 10.2 6.12.0-211.44.1.el10_2
  • perf RHEL 10.2 6.12.0-211.44.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.44.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.44.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.44.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.44.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.44.1.el10_2

red hat advisories RHSA-2026:77634RHSA-2026:51295

  • kernel AlmaLinux 10 6.12.0-211.44.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.44.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.44.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.44.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.44.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.44.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.44.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.44.1.el10_2

almalinux advisories ALSA-2026:51295

  • kernel Rocky Linux 10 6.12.0-211.44.1.el10_2

rocky linux advisories RLSA-2026:51295

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-2026-43186 updated cvss 7.5

kernel: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.44.1.el10_2, perf 6.12.0-211.44.1.el10_2, rtla 6.12.0-211.44.1.el10_2, python3-perf 6.12.0-211.44.1.el10_2, kernel-devel-matched 6.12.0-211.44.1.el10_2, kernel-64k-devel-matched 6.12.0-211.44.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:51295
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.109.1.el10_0, perf 6.12.0-55.109.1.el10_0, rtla 6.12.0-55.109.1.el10_0, python3-perf 6.12.0-55.109.1.el10_0, kernel-devel-matched 6.12.0-55.109.1.el10_0, kernel-64k-devel-matched 6.12.0-55.109.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.44.1.el10_2, kernel-64k 6.12.0-211.44.1.el10_2, kernel-core 6.12.0-211.44.1.el10_2, kernel-tools 6.12.0-211.44.1.el10_2, kernel-modules 6.12.0-211.44.1.el10_2, kernel-64k-core 6.12.0-211.44.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:51295
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.109.1.el10_0, kernel-64k 6.12.0-55.109.1.el10_0, kernel-core 6.12.0-55.109.1.el10_0, kernel-tools 6.12.0-55.109.1.el10_0, kernel-modules 6.12.0-55.109.1.el10_0, kernel-64k-core 6.12.0-55.109.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.44.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.44.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.44.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.44.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.44.1.el10_2
    fixed: vendor fix RHSA-2026:51295
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.109.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.109.1.el10_0
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.44.1.el10_2, kernel-rt-64k 6.12.0-211.44.1.el10_2, kernel-rt-core 6.12.0-211.44.1.el10_2, kernel-rt-modules 6.12.0-211.44.1.el10_2, kernel-rt-64k-core 6.12.0-211.44.1.el10_2, kernel-rt-debug-core 6.12.0-211.44.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:51295
show 4 more
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.109.1.el10_0, kernel-rt-64k 6.12.0-55.109.1.el10_0, kernel-rt-core 6.12.0-55.109.1.el10_0, kernel-rt-modules 6.12.0-55.109.1.el10_0, kernel-rt-64k-core 6.12.0-55.109.1.el10_0, kernel-rt-debug-core 6.12.0-55.109.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:77634
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.44.1.el10_2, kernel-rt-core 6.12.0-211.44.1.el10_2, kernel-rt-modules 6.12.0-211.44.1.el10_2, kernel-rt-debug-core 6.12.0-211.44.1.el10_2, kernel-rt-modules-core 6.12.0-211.44.1.el10_2, kernel-rt-debug-modules 6.12.0-211.44.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:51295
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.109.1.el10_0, kernel-rt-kvm 6.12.0-55.109.1.el10_0, kernel-rt-core 6.12.0-55.109.1.el10_0, kernel-rt-modules 6.12.0-55.109.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.109.1.el10_0, kernel-rt-debug-core 6.12.0-55.109.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:77634
  • 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 rv, perf, rtla, kernel, bpftool, libperf, +83 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
24 d ago

Exploit prediction

0.64% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
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.