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CVE-2026-53221: In the Linux kernel, the following vulnerability has been resolved: ip6_vti: fix incorrect tunnel matching in

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CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-53221 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: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup() In vti6_tnl_lookup(), when an exact match for a tunnel fails, the code falls back to searching for wildcard tunnels: - Tunnels matching the packet's local address, with any remote address wildcard remote). - Tunnels matching the packet's remote address, with any local address (wildcard local). However, vti6 stor

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 53%)
CISA exploited listNo
WeaknessCWE-20
Published2026-06-25
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: >= 3.19 and < 5.10.259 · >= 5.11 and < 5.15.210 · >= 5.16 and < 6.1.176 · >= 6.2 and < 6.6.143 · >= 6.7 and < 6.12.94 · >= 6.13 and < 6.18.36 · >= 6.19 and < 7.0.13 · 7.1 rc1
Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13
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 · python3.11 · FIXED · 3.11.18-1.fc46 · FEDORA-2026-cc775894f4 · source
sudo dnf upgrade --advisory=FEDORA-2026-cc775894f4
Ubuntu 22.04 · linux · FIXED · 5.15.0-194.204
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.15.0-194.204" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 20.04 · linux · FIXED · 5.4.0-241.261
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.4.0-241.261" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 24.04 · linux · FIXED · 6.8.0-142.142
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.8.0-142.142" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 20.04 · linux-hwe-5.15 · FIXED · 5.15.0-194.204~20.04.1
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 "5.15.0-194.204~20.04.1" && echo PATCHED || echo STILL-VULNERABLE
Ubuntu 22.04 · linux-hwe-6.8 · NO FIX YET
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 · 6.12.94-1
sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.94-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 10 · kernel · DEFERRED
RHEL 6 · kernel · NOT AFFECTED
RHEL 7 · kernel · DEFERRED
RHEL 7 · kernel-rt · DEFERRED
RHEL 8 · kernel · DEFERRED
Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1968 · source
sudo dnf update --advisory=ALAS2023-2026-1968

Public exploits and detection

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

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-2026-53221?

linux kernel: upgrade to 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13. Exact commands for each OS are on this page.

Is CVE-2026-53221 being exploited?

CVE-2026-53221 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-2026-53221 affect?

CVE-2026-53221 affects linux kernel. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup() In vti6_tnl_lookup(), when an exact match for a tunnel fails, the code falls back to searching for wildcard tu

How urgent is CVE-2026-53221?

Priority 59/100. 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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