CVE-2026-43501: In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when

Q: How do I fix CVE-2026-43501?

linux kernel: upgrade to 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, 6.18.27, 7.0.4. Exact commands for each OS are on this page.

Q: Is CVE-2026-43501 being exploited?

CVE-2026-43501 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-43501 affect?

CVE-2026-43501 affects linux kernel. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->d

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-43501 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: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the se

Why this priority

Critical severity
Public exploit reference
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 score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-787, CWE-131
Published	2026-05-21
Last modified	2026-10-19

Publisher (CNA): kernel.org · Vendor: linux

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

Am I affected?

Timeline

2026-05-21 13:16 UTCPublished CVE record published
2026-10-19 20:18 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.7 and < 5.10.258 · >= 5.11 and < 5.15.209 · >= 5.16 and < 6.1.175 · >= 6.2 and < 6.6.140 · >= 6.7 and < 6.12.86 · >= 6.13 and < 6.18.27 · >= 6.19 and < 7.0.4 · 7.1 rc1

Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, 6.18.27, 7.0.4

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 ELN · clash-meta · FIXED · 1.19.33-1.eln159 · FEDORA-2026-7dfb64c5e1 · source

sudo dnf upgrade --advisory=FEDORA-2026-7dfb64c5e1

Fedora 46 · vulkan-utility-libraries · FIXED · 1.4.363.0-1.fc46 · FEDORA-2026-994176daf5 · source

sudo dnf upgrade --advisory=FEDORA-2026-994176daf5

Debian 12 · linux · FIXED · 6.1.176-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.176-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.86-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.86-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · FIXED · kernel-6.12.0-211.22.1.el10_2

sudo dnf upgrade --advisory=RHSA-2026:25191 rpm -q kernel

RHEL 10.0 Extended Update Support · kernel · FIXED · kernel-6.12.0-55.82.1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:27731 rpm -q kernel

RHEL 9 · kernel · FIXED · kernel-5.14.0-687.15.1.el9_8

sudo dnf upgrade --advisory=RHSA-2026:25217 rpm -q kernel

RHEL 9.2 Update Services for SAP Solutions · kernel · FIXED · kernel-5.14.0-284.178.1.el9_2

sudo dnf upgrade --advisory=RHSA-2026:34095 rpm -q kernel

RHEL 9.2 Update Services for SAP Solutions · kernel-rt · FIXED · kernel-rt-5.14.0-284.178.1.rt14.463.el9_2

sudo dnf upgrade --advisory=RHSA-2026:33900 rpm -q kernel-rt

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1754 · source

sudo dnf update --advisory=ALAS2023-2026-1754

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: Anyone202/cybermeowfia-termux (7 stars)
GitHub PoC: ngtuonghung/CVE-2026-43501 (0 stars)
Write-up: bugzilla.redhat.com/show_bug.cgi?id=2480457
Write-up: cert-portal.siemens.com/productcert/html/ssa-019113.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-457936.html

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-2026-43501?

linux kernel: upgrade to 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, 6.18.27, 7.0.4. Exact commands for each OS are on this page.

Is CVE-2026-43501 being exploited?

CVE-2026-43501 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-2026-43501 affect?

CVE-2026-43501 affects linux kernel. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->d

How urgent is CVE-2026-43501?

Priority 66/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

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References

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