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High · 7.5 CVE-2026-72502 EUVD-2026-59401GHSA-cg8c-jghv-84p9

tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)

Published Aug 15, 2026 · Updated Oct 16, 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-5.4 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-7.0 Package: linux-aws-fips Package: linux-aws-hwe Package: linux-azure Package: linux-azure-4.15 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-5.4 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-4.15 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-5.4 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-5.4 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-5.4 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-iot 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-5.4 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-5.4 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:

tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)

When MTU is large, ip6_default_advmss() can return IPV6_MAXPLEN (65535).
This is interpreted by TCP as mss_clamp, allowing the MSS to reach 65535.

However, 0xFFFF is also used as a magic value GSO_BY_FRAGS in the kernel.
If a TCP packet with gso_size=0xFFFF is passed to skb_segment(), it will
be mistakenly treated as GSO_BY_FRAGS, leading to a NULL pointer
dereference because local TCP packets do not use frag_list.

Fix this by returning min(IPV6_MAXPLEN, GSO_BY_FRAGS - 1) (65534) from
ip6_default_advmss() when MTU is large.

Also update the stale comment in ip6_default_advmss() which suggested
that IPV6_MAXPLEN is returned to mean "any MSS".

Affected products

VendorProductAffectedFixed
Linux Linux 4.8 5.10.261

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 7.1.5-1 —
Debian 13 linux 6.12.100-1 —
Debian 12 linux 6.1.180-1 —
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1033.38 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield 5.15.0-1101.103 —
Ubuntu 26.04 LTS linux 7.0.0-38.38 USN-8887-1
Ubuntu 26.04 LTS linux-aws +1 7.0.0-1014.14 USN-8887-1
Ubuntu 26.04 LTS linux-azure 7.0.0-1017.17 USN-8888-1
Ubuntu 26.04 LTS linux-azure-fde 7.0.0-1016.16 USN-8888-1
Ubuntu 26.04 LTS linux-gke 7.0.0-1008.9 USN-8887-1
Ubuntu 26.04 LTS linux-ibm +1 7.0.0-1015.15 USN-8889-1, USN-8887-1
Ubuntu 26.04 LTS linux-nvidia 7.0.0-1025.26 USN-9043-1
Ubuntu 26.04 LTS linux-nvidia-bos 7.0.0-2022.23 USN-9003-1
Ubuntu 26.04 LTS linux-oracle 7.0.0-1013.13 USN-8887-1
Ubuntu 26.04 LTS linux-raspi 7.0.0-1023.23 USN-9021-1
Ubuntu 26.04 LTS linux-riscv +1 7.0.0-38.38.1 USN-8887-1
Ubuntu 24.04 LTS linux 6.8.0-147.147 USN-8917-1
Ubuntu 24.04 LTS linux-aws +1 6.8.0-1067.70 USN-9024-1, USN-8917-1
Ubuntu 24.04 LTS linux-aws-7.0 +1 7.0.0-1014.14~24.04.1 USN-8887-3, USN-8887-2
Ubuntu 24.04 LTS linux-azure-7.0 7.0.0-1017.17~24.04.1 USN-8888-2
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1069.76 USN-8918-1
Ubuntu 24.04 LTS linux-azure-fde-7.0 7.0.0-1016.16~24.04.1 USN-8888-2
Ubuntu 24.04 LTS linux-gcp +1 6.8.0-1071.79 USN-8918-1, USN-8917-1
Ubuntu 24.04 LTS linux-gke 6.8.0-1066.74 USN-8917-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1052.56 USN-8917-1
Ubuntu 24.04 LTS linux-hwe-7.0 7.0.0-38.38~24.04.4 USN-8887-3
Ubuntu 24.04 LTS linux-ibm 6.8.0-1067.68 USN-8917-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-147.147.1 USN-8917-1
Ubuntu 24.04 LTS linux-nvidia-7.0 7.0.0-1024.25~24.04.1 USN-9003-1
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1067.70.1 USN-9040-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1036.39 USN-8886-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1064.67 USN-8917-1
Ubuntu 24.04 LTS linux-oracle-7.0 7.0.0-1013.13~24.04.1 USN-8887-3
Ubuntu 24.04 LTS linux-raspi 6.8.0-1068.72 USN-9025-1
Ubuntu 24.04 LTS linux-riscv +29 No fix yet —
Ubuntu 24.04 LTS linux-riscv-7.0 7.0.0-38.38.1~24.04.1 —
Ubuntu 24.04 LTS linux-vmware 6.8.0-1008.8 —
Ubuntu 22.04 LTS linux 5.15.0-198.208 USN-8875-1
Ubuntu 22.04 LTS linux-aws 5.15.0-1117.124 USN-8875-1
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1069.74~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-azure 5.15.0-1123.132 USN-8875-1
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1073.82~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-azure-fde 5.15.0-1122.131 USN-8876-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1071.78~22.04.1 USN-9026-1
Ubuntu 22.04 LTS linux-gcp 5.15.0-1118.128 USN-8877-1
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1073.81~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-gke 5.15.0-1113.119 USN-8875-1
Ubuntu 22.04 LTS linux-gkeop 5.15.0-1100.108 USN-8875-1
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 5.15.0-1111.115 USN-8875-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1069.70~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-intel-iotg 5.15.0-1112.118 USN-8875-1
Ubuntu 22.04 LTS linux-kvm 5.15.0-1109.114 USN-8875-1
Ubuntu 22.04 LTS linux-lowlatency 5.15.0-195.205 USN-8875-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-149.149.1~22.04.1 USN-9024-1
Ubuntu 22.04 LTS linux-nvidia 5.15.0-1112.113 USN-8875-2
Ubuntu 22.04 LTS linux-nvidia-tegra 5.15.0-1070.72 USN-8963-1
Ubuntu 22.04 LTS linux-nvidia-tegra-igx 5.15.0-1059.59 USN-8963-1
Ubuntu 22.04 LTS linux-oracle 5.15.0-1114.120 USN-8875-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1067.71~22.04.1 USN-9025-1
Ubuntu 22.04 LTS linux-raspi 5.15.0-1113.116 USN-9029-1
Ubuntu 22.04 LTS linux-riscv +33 No fix yet —
Ubuntu 22.04 LTS linux-xilinx-zynqmp 5.15.0-1080.84 USN-8875-1
Show 16 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 6.8.0-2056.58 USN-9025-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1062.63 USN-8917-1
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-intel-iot-realtime 5.15.0-1109.111 USN-8875-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime 5.15.0-1116.125 USN-8875-1
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1064.65~22.04.1 USN-9024-1
Ubuntu Pro FIPS 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1067.70+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-147.147+fips1 USN-8917-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips +1 6.8.0-1071.79+fips1 USN-8918-1, USN-8917-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-aws-fips 5.15.0-1117.124+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-azure-fips 5.15.0-1123.132+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips 5.15.0-198.208+fips1 USN-8875-1
Ubuntu Pro FIPS-updates 22.04 LTS linux-gcp-fips 5.15.0-1118.128+fips1 USN-8877-1
Ubuntu Pro FIPS-updates 20.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-updates 18.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro FIPS-preview 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux +10 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 5.15.0-1117.124~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-azure-5.15 5.15.0-1123.132~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-azure-fde-5.15 5.15.0-1122.131~20.04.1 USN-8875-1
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 5.15.0-198.208~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-ibm-5.15 +1 5.15.0-1111.115~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-intel-iotg-5.15 5.15.0-1112.118~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-lowlatency-hwe-5.15 5.15.0-195.205~20.04.1 USN-8875-1
Ubuntu Pro 20.04 LTS linux-nvidia-tegra-5.15 5.15.0-1070.72~20.04.1 USN-8963-1
Ubuntu Pro 20.04 LTS linux-oracle-5.15 5.15.0-1114.120~20.04.1 USN-8879-1
Ubuntu Pro 18.04 LTS linux +12 No fix yet —
Ubuntu Pro 16.04 LTS linux-gcp +4 No fix yet —
Ubuntu Pro 14.04 LTS linux-azure No fix yet —
ReleasePackageFixed inAdvisory
SLES 15 SP7 kernel-64kb +7 6.4.0-150700.53.81.1 SUSE-SU-2026:4254-1
SLES 15 SP7 kernel-default-base 6.4.0-150700.53.81.1.150700.17.45.1 SUSE-SU-2026:4254-1
SLES 12 SP5 kernel-syms +2 4.12.14-122.328.1 SUSE-SU-2026:4282-1
Show 8 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 6.1 kernel-default-base 6.4.0-52.1.21.34 SUSE-SU-2026:23529-1
SLE Micro 6.1 kernel-rt +4 6.4.0-52.1 SUSE-SU-2026:23529-1, SUSE-SU-2026:23528-1
SLE Micro 6.0 kernel-default-base 6.4.0-52.1.21.36 SUSE-SU-2026:23481-1
SLE Micro 6.0 kernel-rt +4 6.4.0-52.1 SUSE-SU-2026:23481-1, SUSE-SU-2026:23477-1
SLE Live Patching 15 SP7 kernel-default 6.4.0-150700.53.81.1 SUSE-SU-2026:4254-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7-RT_Update_20 1-150700.1.3.1 SUSE-SU-2026:4120-1
SLE Live Patching 15 SP7 kernel-livepatch-SLE15-SP7_Update_21 1-150700.15.3.1 SUSE-SU-2026:4254-1
SLE Live Patching 12 SP5 kernel-default 4.12.14-122.328.1 SUSE-SU-2026:4282-1
SLE Live Patching 12 SP5 kgraft-patch-SLE12-SP5_Update_87 1-8.5.1 SUSE-SU-2026:4282-1
SUSE Real Time Module 15 SP7 kernel-rt +2 6.4.0-150700.7.75.1 SUSE-SU-2026:4120-1
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-6.18.41-94.142 +2 1:1.0-0.amzn2023 ALAS2023-2026-2071, ALAS2023-2026-2058, ALAS2023-2026-2057
Amazon Linux 2023 perf +11 1:6.1.180-225.360.amzn2023 ALAS2023-2026-2058
Amazon Linux 2023 perf6.12 +11 1:6.12.100-125.179.amzn2023 ALAS2023-2026-2057
Amazon Linux 2023 perf6.18 +12 1:6.18.41-94.142.amzn2023 ALAS2023-2026-2071

Oracle Linux

ReleasePackageFixed inAdvisory
Oracle Linux 9 kernel-uek +34 6.12.0-206.104.3.3.el10uek ELSA-2026-500248
Oracle Linux 8 bpftool +18 5.15.0-324.217.5.2.el9uek ELSA-2026-500249

Advisories 43

References