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Critical · 9.8 CVE-2026-63993 EUVD-2026-45566GHSA-p6vc-4hvx-xvcw

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

Published Jul 19, 2026 · Updated Oct 19, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.15 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.14 Package: linux-aws-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-aws-6.8 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-7.0 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.17 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fde-7.0 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gcp-6.8 Package: linux-gcp-7.0 Package: linux-gcp-fips Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-7.0 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-7.0 Package: linux-nvidia-bos Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oem-7.0 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.15 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.5 Package: linux-oracle-6.8 Package: linux-oracle-7.0 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 Package: linux-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-riscv-7.0 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

skb_tunnel_check_pmtu() can change skb->head.

Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.

Use instead ip_hdr(skb) as done in drivers/net/bareudp.c
and drivers/net/geneve.c.

Found by Sashiko.

Affected products

VendorProductAffectedFixed
Linux Linux 5.9 5.10.259

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 linux 7.0.12-1 —
Debian 13 linux 6.12.94-1 —
Debian 12 linux 6.1.176-1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1031.36 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1100.102 —
Ubuntu 26.04 LTS linux 7.0.0-28.28 —
Ubuntu 26.04 LTS linux-aws +2 7.0.0-1009.9 USN-8618-1, USN-8603-1
Ubuntu 26.04 LTS linux-gcp +1 7.0.0-1008.8 USN-8593-1
Ubuntu 26.04 LTS linux-gke 7.0.0-1003.4 —
Ubuntu 26.04 LTS linux-ibm +1 7.0.0-1010.10 USN-8603-1, USN-8593-1
Ubuntu 26.04 LTS linux-nvidia 7.0.0-1016.16 USN-8663-1
Ubuntu 26.04 LTS linux-nvidia-bos 7.0.0-2016.16 USN-8664-1
Ubuntu 26.04 LTS linux-raspi 7.0.0-1015.15 USN-8618-1
Ubuntu 26.04 LTS linux-riscv +1 7.0.0-28.28.1 —
Ubuntu 24.04 LTS linux 6.8.0-142.142 USN-8817-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1065.68 USN-8817-3
Ubuntu 24.04 LTS linux-azure 6.8.0-1068.76 USN-8817-1
Ubuntu 24.04 LTS linux-azure-7.0 7.0.0-1014.14~24.04.1 USN-8728-2
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1066.73 USN-8817-1
Ubuntu 24.04 LTS linux-azure-fde-7.0 7.0.0-1013.13~24.04.1 —
Ubuntu 24.04 LTS linux-gcp 6.8.0-1069.77 USN-8817-1
Ubuntu 24.04 LTS linux-gcp-7.0 +1 7.0.0-1011.11~24.04.1 USN-8728-3, USN-8728-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1064.72 USN-8817-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1050.54 USN-8817-1
Ubuntu 24.04 LTS linux-hwe-7.0 7.0.0-28.28~24.04.1 —
Ubuntu 24.04 LTS linux-ibm 6.8.0-1065.66 USN-8817-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-142.142.1 USN-8817-1
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1063.66 USN-8842-1
Ubuntu 24.04 LTS linux-nvidia-7.0 7.0.0-1016.16~24.04.1 USN-8663-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1063.66.1 USN-8842-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1035.38 USN-8781-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1062.65 USN-8817-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1065.69 USN-8817-1
Ubuntu 24.04 LTS linux-riscv +29 No fix yet —
Ubuntu 24.04 LTS linux-riscv-7.0 7.0.0-28.28.1~24.04.3 —
Ubuntu 24.04 LTS linux-vmware 6.8.0-1008.8 —
Ubuntu 22.04 LTS linux +1 5.15.0-194.204 USN-8818-4, USN-8818-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1116.123 USN-8818-1
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1065.68~22.04.1 USN-8817-3
Ubuntu 22.04 LTS linux-azure 5.15.0-1122.131 USN-8818-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1068.76~22.04.1 USN-8817-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1121.130 USN-8818-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1066.73~22.04.1 USN-8817-1
Ubuntu 22.04 LTS linux-gcp 5.15.0-1117.127 USN-8818-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1069.77~22.04.1 USN-8817-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1112.118 USN-8818-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1099.107 USN-8818-1
Ubuntu 22.04 LTS linux-hwe-6.8 6.8.0-149.149~22.04.1 USN-9066-1
Ubuntu 22.04 LTS linux-ibm 5.15.0-1110.114 USN-8818-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1066.67~22.04.1 USN-8906-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1111.117 USN-8818-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1108.113 USN-8818-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-142.142.1~22.04.1 USN-8817-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1111.112 USN-8818-4
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1063.66~22.04.1 USN-8842-1
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1068.70 USN-8818-5
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1057.57 USN-8818-5
Ubuntu 22.04 LTS linux-oracle 5.15.0-1113.119 USN-8818-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1062.65~22.04.1 USN-8817-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1110.113 USN-8871-1
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 22.04 LTS linux-riscv-6.8 6.8.0-142.142~22.04.1 —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1079.83 USN-8818-1
Show 9 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2054.56 USN-8817-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1060.61 USN-8817-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1108.110 USN-8818-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1115.124 USN-8818-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1060.61~22.04.1 USN-8817-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1065.68+fips1 USN-8817-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-142.142+fips1 USN-8817-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips +1 6.8.0-1068.76+fips1 USN-8817-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1116.123+fips1 USN-8818-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1122.131+fips1 USN-8818-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-194.204+fips1 USN-8818-6
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1116.126+fips1 USN-8818-1
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1116.123~20.04.1 USN-8818-3
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1122.131~20.04.1 USN-8818-3
Ubuntu Pro 20.04 LTS linux-azure-fde-5.15 5.15.0-1121.130~20.04.1 USN-8818-3
Ubuntu Pro 20.04 LTS linux-gcp-5.15 5.15.0-1118.128~20.04.1 USN-8878-1
Ubuntu Pro 20.04 LTS linux-hwe-5.15 +1 5.15.0-194.204~20.04.1 USN-8818-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 +1 5.15.0-1110.114~20.04.1 USN-8818-2
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1111.117~20.04.1 USN-8818-3
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1068.70~20.04.1 USN-8849-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1114.120~20.04.1 USN-8879-1
ReleasePackageFixed inAdvisory
RHEL 10 rv +76 6.12.0-211.52.1.el10_2 RHSA-2026:64775
RHEL 9 rv +75 5.14.0-687.55.1.el9_8 RHSA-2026:76739
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
RHEL 10.0 EUS rv +77 6.12.0-55.111.1.el10_0 RHSA-2026:83707

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 10 kernel 6.12.0-211.52.1.el10_2 RLSA-2026:64775
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +7 6.4.0-150700.53.84.1 SUSE-SU-2026:4706-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.84.1.150700.17.47.1 SUSE-SU-2026:4706-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1
SLES for SAP 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLES 16.0 kernel-64kb +8 6.12.0-160000.38.1 SUSE-SU-2026:23902-1, SUSE-SU-2026:23897-1
SLES 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23902-1
SLE Micro 6.2 kernel-default-base 6.12.0-160000.38.1.160000.2.23 SUSE-SU-2026:23887-1
SLE Micro 6.2 kernel-rt +5 6.12.0-160000.38.1 SUSE-SU-2026:23887-1, SUSE-SU-2026:23881-1
SLE Micro 6.2 podman 5.4.2-160000.6.1 SUSE-SU-2026:24182-1
SLE Micro 6.1 kernel-default-base 6.4.0-159998.53.1.159998.21.38 SUSE-SU-2026:24181-1
SLE Micro 6.1 kernel-rt +4 6.4.0-159998.53.1 SUSE-SU-2026:24182-1, SUSE-SU-2026:24181-1
SLE Micro 6.0 kernel-default-base 6.4.0-159998.53.1.159998.21.38 SUSE-SU-2026:24315-1
SLE Micro 6.0 kernel-rt +4 6.4.0-159998.53.1 SUSE-SU-2026:24316-1, SUSE-SU-2026:24315-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.84.1 SUSE-SU-2026:4706-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_21 1-150700.1.3.1 SUSE-SU-2026:4640-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_22 1-150700.15.3.1 SUSE-SU-2026:4706-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.78.1 SUSE-SU-2026:4640-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 kernel-default-base 6.12.0-160000.38.1.160000.2.22 openSUSE-SU-2026:21910-1
openSUSE Leap 16.0 kernel-rt +11 6.12.0-160000.38.1 openSUSE-SU-2026:21910-1

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 kernel-livepatch-6.18.35-68.127 +2 1:1.0-0.amzn2023 ALAS2023-2026-1968, ALAS2023-2026-1924, ALAS2023-2026-1881
Amazon Linux 2023 perf +11 1:6.1.176-220.358.amzn2023 ALAS2023-2026-1924
Amazon Linux 2023 perf6.12 +11 1:6.12.94-123.174.amzn2023 ALAS2023-2026-1968
Amazon Linux 2023 perf6.18 +12 1:6.18.35-68.127.amzn2023 ALAS2023-2026-1881

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-206.104.3.3.el10uek ELSA-2026-500248
Oracle Linux 9 rv +28 5.14.0-687.56.1.el9_8 ELSA-2026-76739

Advisories 46

References