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CVE-2026-43186: In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: fix heap buffer overflow in _

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CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-43186 is a critical-severity flaw (CVSS 9.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

  • Critical severity
  • CISA SSVC: automatable with total technical impact
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.6% (top 49%)
CISA exploited listNo
WeaknessCWE-787, CWE-122
Published2026-05-06
Last modified2026-10-19
Publisher (CNA): kernel.org · Vendor: linux

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Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

linux linux kernel UPGRADE
Affected: >= 5.15 and < 5.15.202 · >= 5.16 and < 6.1.165 · >= 6.2 and < 6.6.128 · >= 6.7 and < 6.12.75 · >= 6.13 and < 6.18.16 · >= 6.19 and < 6.19.6
Fixed in: 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · fzssh · FIXED · 1.4.0-2.fc46 · FEDORA-2026-8004fcd067 · source
sudo dnf upgrade --advisory=FEDORA-2026-8004fcd067
Ubuntu 25.10 · linux · FIXED · 6.17.0-40.40
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.17.0-40.40" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 24.04 · linux · FIXED · 6.8.0-134.134
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.8.0-134.134" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 22.04 · linux · FIXED · 5.15.0-185.195
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.15.0-185.195" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 20.04 · linux · NOT AFFECTED
Ubuntu 20.04 · linux-hwe-5.15 · FIXED · 5.15.0-185.195~20.04.1
sudo apt update && sudo apt install --only-upgrade linux-hwe-5.15 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux-hwe-5.15)" ge "5.15.0-185.195~20.04.1" && echo PATCHED || echo STILL-VULNERABLE
Debian 12 · linux · FIXED · 6.1.170-1
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.170-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · linux · FIXED · 6.12.85-1
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.85-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 10 · kernel · FIXED · kernel-6.12.0-211.44.1.el10_2
sudo dnf upgrade --advisory=RHSA-2026:51295 rpm -q kernel
RHEL 10.0 Extended Update Support · kernel · FIXED · kernel-6.12.0-55.109.1.el10_0
sudo dnf upgrade --advisory=RHSA-2026:77634 rpm -q kernel
RHEL 6 · kernel · DEFERRED
RHEL 7 · kernel · NOT AFFECTED
RHEL 7 · kernel-rt · NOT AFFECTED
Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1702 · source
sudo dnf update --advisory=ALAS2023-2026-1702
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-43186?

linux kernel: upgrade to 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6. Exact commands for each OS are on this page.

Is CVE-2026-43186 being exploited?

CVE-2026-43186 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-43186 affect?

CVE-2026-43186 affects linux kernel. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-43186?

Priority 60/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities

Related CVEs

References

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