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Fencer Vulns
critical 9.8

CVE-2026-64132 in the critical feed json

ipv6: ioam: refresh hdr pointer before ioam6_event()

published 2026-07-19 3 mo ago modified 2026-08-13 2 mo ago also EUVD-2026-45817

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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

ipv6: ioam: refresh hdr pointer before ioam6_event()

Reported by Sashiko:

In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer:

if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len)) goto drop;

/* Trace pointer may have changed */ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb) + optoff + sizeof(*hdr));

ioam6_fill_trace_data(skb, ns, trace, true);

ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev), GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);

If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer.

This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

Patch / fix

  • Linux Linux 6.12.92, 6.18.34, 7.0.11, 7.1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-64132

  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1003.4
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-28.28.1

ubuntu advisories UBUNTU-CVE-2026-64132

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-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.39.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.39.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.39.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.39.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.39.1.160000.2.26
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.39.1
  • kernel-azure SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.39.1
  • kernel-obs-qa SLES for SAP applications 16.0, SLES 16.0 6.12.0-160000.39.1

suse advisories SUSE-SU-2026:24197-1SUSE-SU-2026:24184-1SUSE-SU-2026:24235-1SUSE-SU-2026:24179-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.39.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.39.1

opensuse advisories openSUSE-SU-2026:22091-1

  • kernel AlmaLinux 10 6.12.0-211.63.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.63.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.63.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.63.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.63.1.el10_2

almalinux advisories ALSA-2026:76738

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-2026-64132 updated cvss 7.0

kernel: ipv6: ioam: refresh hdr pointer before ioam6_event()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    under investigation
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.63.1.el10_2 Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.63.1.el10_2, perf 6.12.0-211.63.1.el10_2, rtla 6.12.0-211.63.1.el10_2, python3-perf 6.12.0-211.63.1.el10_2, kernel-devel-matched 6.12.0-211.63.1.el10_2, kernel-64k-devel-matched 6.12.0-211.63.1.el10_2, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.63.1.el10_2, kernel-64k 6.12.0-211.63.1.el10_2, kernel-core 6.12.0-211.63.1.el10_2, kernel-tools 6.12.0-211.63.1.el10_2, kernel-modules 6.12.0-211.63.1.el10_2, kernel-64k-core 6.12.0-211.63.1.el10_2, +28 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.63.1.el10_2 Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.63.1.el10_2 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.63.1.el10_2, kernel-rt-64k 6.12.0-211.63.1.el10_2, kernel-rt-core 6.12.0-211.63.1.el10_2, kernel-rt-modules 6.12.0-211.63.1.el10_2, kernel-rt-64k-core 6.12.0-211.63.1.el10_2, kernel-rt-debug-core 6.12.0-211.63.1.el10_2, +14 more
    +1 more products
    Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.63.1.el10_2, kernel-rt-core 6.12.0-211.63.1.el10_2, kernel-rt-modules 6.12.0-211.63.1.el10_2, kernel-rt-debug-core 6.12.0-211.63.1.el10_2, kernel-rt-modules-core 6.12.0-211.63.1.el10_2, kernel-rt-debug-modules 6.12.0-211.63.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:76738
  • 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

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% 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.