CVE-2026-98306: seg6: set IPSKB_L3SLAVE from IP6SKB_L3SLAVE on IPIP decapsulation

Published Oct 6, 2026
·
Updated

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

seg6: set IPSKBL3SLAVE from IP6SKBL3SLAVE on IPIP decapsulation

When an SRv6 packet arrives on an interface enslaved to a VRF, vrfip6rcv() sets IP6SKBL3SLAVE in IP6CB, but decapandvalidate() has never set IPSKBL3SLAVE in IPCB. The bit stayed clear in the common case, and with CONFIGIPV6MIP6 the leftover fragmaxsize of a reassembled outer packet could even set it, with no VRF involved. Commit 44930446dde4 ("ipv6: seg6: clear IPv4 control block on IPIP decapsulation") then made the unreliable bit reliably clear.

The effect of the missing flag is visible with End.DX4 when a delivery to a local address of the node reaches the socket lookup. For example, a UDP socket bound to the enslaved ingress interface does not receive any of the decapsulated packets, while an unbound socket outside the VRF does. This contradicts Documentation/networking/vrf.rst: by default the scope of an unbound UDP or TCP socket is limited to the default VRF.

Set IPSKBL3SLAVE for IPv4 in decapandvalidate(), which already does the same for IPv6. The socket lookup then matches the decapsulated packet like any other packet received on that enslaved interface. Such a packet matches an unbound UDP or TCP socket only when udpl3mdevaccept or tcpl3mdevaccept is set.

Affected Software

257 affected componentsFixes available
Linux Linux kernel
Microsoft azl3 kernel 6.6.157.1-1<6.6.158.1-1
6.6.158.1-1
debian/linux<=6.1.176-1, <=6.12.107-1
6.1.190-16.12.115-27.2.12-17.2.15-1
debian/linux-6.12
6.12.113-1~deb12u1
ubuntu/linux-azure*
ubuntu/linux-aws-hwe*
ubuntu/linux-azure*
ubuntu/linux-gcp*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oracle*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-aws-5.4*
ubuntu/linux-azure*
ubuntu/linux-azure-4.15*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-5.4*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-4.15*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gcp-5.4*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-5.4*
ubuntu/linux-hwe-edge*
ubuntu/linux-ibm-5.4*
ubuntu/linux-kvm*
ubuntu/linux-oem*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-oracle-5.4*
ubuntu/linux-raspi-5.4*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.15<5.15.0-1119.126~20.04.1
5.15.0-1119.126~20.04.1
ubuntu/linux-aws-5.8*
ubuntu/linux-azure*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.15<5.15.0-1125.134~20.04.1
5.15.0-1125.134~20.04.1
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.15<5.15.0-1124.133~20.04.1
5.15.0-1124.133~20.04.1
ubuntu/linux-bluefield*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.15<5.15.0-1120.130~20.04.1
5.15.0-1120.130~20.04.1
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-gkeop*
ubuntu/linux-gkeop-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.15<5.15.0-202.212~20.04.1
5.15.0-202.212~20.04.1
ubuntu/linux-hwe-5.8*
ubuntu/linux-ibm*
ubuntu/linux-ibm-5.15<5.15.0-1113.117~20.04.1
5.15.0-1113.117~20.04.1
ubuntu/linux-intel-5.13*
ubuntu/linux-intel-iotg-5.15<5.15.0-1114.120~20.04.1
5.15.0-1114.120~20.04.1
ubuntu/linux-iot*
ubuntu/linux-kvm*
ubuntu/linux-lowlatency-hwe-5.15<5.15.0-197.207~20.04.1
5.15.0-197.207~20.04.1
ubuntu/linux-nvidia-tegra-5.15<5.15.0-1070.72~20.04.1
5.15.0-1070.72~20.04.1
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.15<5.15.0-1116.122~20.04.1
5.15.0-1116.122~20.04.1
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.15<5.15.0-1113.117~20.04.2
5.15.0-1113.117~20.04.2
ubuntu/linux-riscv-5.8*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<5.15.0-202.212
5.15.0-202.212
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws<5.15.0-1119.126
5.15.0-1119.126
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-aws-6.8*
ubuntu/linux-azure<5.15.0-1125.134
5.15.0-1125.134
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-6.8*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-azure-fde-6.8*
ubuntu/linux-gcp<5.15.0-1120.130
5.15.0-1120.130
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gcp-6.8*
ubuntu/linux-gke<5.15.0-1115.121
5.15.0-1115.121
ubuntu/linux-gkeop<5.15.0-1102.110
5.15.0-1102.110
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-ibm<5.15.0-1113.117
5.15.0-1113.117
ubuntu/linux-ibm-6.8*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-intel-iotg<5.15.0-1114.120
5.15.0-1114.120
ubuntu/linux-kvm<5.15.0-1111.116
5.15.0-1111.116
ubuntu/linux-lowlatency<5.15.0-197.207
5.15.0-197.207
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-lowlatency-hwe-6.8*
ubuntu/linux-nvidia<5.15.0-1114.115
5.15.0-1114.115
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-nvidia-6.8*
ubuntu/linux-nvidia-tegra<5.15.0-1070.72
5.15.0-1070.72
ubuntu/linux-nvidia-tegra-igx<5.15.0-1059.59
5.15.0-1059.59
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle<5.15.0-1116.122
5.15.0-1116.122
ubuntu/linux-oracle-6.5*
ubuntu/linux-oracle-6.8*
ubuntu/linux-raspi*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-riscv-6.8*
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-bluefield<5.15.0-1103.105
5.15.0-1103.105
ubuntu/linux-intel-iot-realtime<5.15.0-1111.115
5.15.0-1111.115
ubuntu/linux-realtime<5.15.0-1118.127
5.15.0-1118.127
ubuntu/linux-realtime-6.8*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips<5.15.0-1119.126+fips1
5.15.0-1119.126+fips1
ubuntu/linux-azure-fips<5.15.0-1125.134+fips1
5.15.0-1125.134+fips1
ubuntu/linux-fips<5.15.0-202.212+fips1
5.15.0-202.212+fips1
ubuntu/linux-gcp-fips<5.15.0-1120.130+fips1
5.15.0-1120.130+fips1
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-6.14*
ubuntu/linux-aws-6.17*
ubuntu/linux-aws-7.0*
ubuntu/linux-azure*
ubuntu/linux-azure-6.11*
ubuntu/linux-azure-6.14*
ubuntu/linux-azure-6.17*
ubuntu/linux-azure-7.0*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-6.14*
ubuntu/linux-azure-fde-6.17*
ubuntu/linux-azure-fde-7.0*
ubuntu/linux-azure-nvidia*
ubuntu/linux-azure-nvidia-6.14*
ubuntu/linux-gcp*
ubuntu/linux-gcp-6.11*
ubuntu/linux-gcp-6.14*
ubuntu/linux-gcp-7.0*
ubuntu/linux-gke*
ubuntu/linux-gkeop*
ubuntu/linux-hwe-6.11*
ubuntu/linux-hwe-6.14*
ubuntu/linux-hwe-6.17*
ubuntu/linux-hwe-7.0<7.0.0-42.42~24.04.1
7.0.0-42.42~24.04.1
ubuntu/linux-ibm*
ubuntu/linux-lowlatency*
ubuntu/linux-lowlatency-hwe-6.11*
ubuntu/linux-nvidia*
ubuntu/linux-nvidia-6.11*
ubuntu/linux-nvidia-6.17*
ubuntu/linux-nvidia-7.0*
ubuntu/linux-nvidia-lowlatency*
ubuntu/linux-nvidia-tegra*
ubuntu/linux-oem-6.11*
ubuntu/linux-oem-6.14*
ubuntu/linux-oem-6.17*
ubuntu/linux-oem-6.8*
ubuntu/linux-oracle*
ubuntu/linux-oracle-6.14*
ubuntu/linux-oracle-6.17*
ubuntu/linux-oracle-7.0*
ubuntu/linux-raspi*
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-6.14*
ubuntu/linux-riscv-6.17*
ubuntu/linux-riscv-7.0<7.0.0-42.42.1~24.04.1
7.0.0-42.42.1~24.04.1
ubuntu/linux-xilinx*
ubuntu/linux-bluefield*
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-realtime-6.14*
ubuntu/linux-realtime-6.17*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<7.0.0-42.42
7.0.0-42.42
ubuntu/linux-aws<7.0.0-1016.17
7.0.0-1016.17
ubuntu/linux-azure*
ubuntu/linux-azure-fde*
ubuntu/linux-gcp<7.0.0-1016.18
7.0.0-1016.18
ubuntu/linux-gke*
ubuntu/linux-ibm<7.0.0-1017.17
7.0.0-1017.17
ubuntu/linux-nvidia*
ubuntu/linux-nvidia-bos*
ubuntu/linux-oem-7.0<7.0.0-1017.17
7.0.0-1017.17
ubuntu/linux-oracle<7.0.0-1015.16
7.0.0-1015.16
ubuntu/linux-raspi*
ubuntu/linux-realtime*
ubuntu/linux-riscv<7.0.0-42.42.1
7.0.0-42.42.1
linux/kernel>=4.14.0<5.10.271
5.10.271
linux/kernel>=5.11.0<5.15.222
5.15.222
linux/kernel>=5.16.0<6.1.189
6.1.189
linux/kernel>=6.2.0<6.6.158
6.6.158
linux/kernel>=6.7.0<6.12.112
6.12.112
linux/kernel>=6.13.0<6.18.54
6.18.54
linux/kernel>=6.19.0<7.2.8
7.2.8

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.6.158.1-1
  2. Upgrade

    Upgrade debian/linux to a version that resolves this vulnerability.

    Fixed in 6.1.190-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1
  3. Upgrade

    Upgrade debian/linux-6.12 to a version that resolves this vulnerability.

    Fixed in 6.12.113-1~deb12u1
  4. Upgrade

    Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1119.126~20.04.1
  5. Upgrade

    Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1125.134~20.04.1
  6. Upgrade

    Upgrade ubuntu/linux-azure-fde-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1124.133~20.04.1
  7. Upgrade

    Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1120.130~20.04.1
  8. Upgrade

    Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-202.212~20.04.1
  9. Upgrade

    Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1113.117~20.04.1
  10. Upgrade

    Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1114.120~20.04.1
  11. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-197.207~20.04.1
  12. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1070.72~20.04.1
  13. Upgrade

    Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1116.122~20.04.1
  14. Upgrade

    Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.

    Fixed in 5.15.0-1113.117~20.04.2
  15. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 5.15.0-202.212
  16. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 5.15.0-1119.126
  17. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 5.15.0-1125.134
  18. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.15.0-1120.130
  19. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 5.15.0-1115.121
  20. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 5.15.0-1102.110
  21. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 5.15.0-1113.117
  22. Upgrade

    Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.

    Fixed in 5.15.0-1114.120
  23. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.15.0-1111.116
  24. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 5.15.0-197.207
  25. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 5.15.0-1114.115
  26. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.

    Fixed in 5.15.0-1070.72
  27. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra-igx to a version that resolves this vulnerability.

    Fixed in 5.15.0-1059.59
  28. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.15.0-1116.122
  29. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 5.15.0-1103.105
  30. Upgrade

    Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1111.115
  31. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 5.15.0-1118.127
  32. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1119.126+fips1
  33. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1125.134+fips1
  34. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-202.212+fips1
  35. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 5.15.0-1120.130+fips1
  36. Upgrade

    Upgrade ubuntu/linux-hwe-7.0 to a version that resolves this vulnerability.

    Fixed in 7.0.0-42.42~24.04.1
  37. Upgrade

    Upgrade ubuntu/linux-riscv-7.0 to a version that resolves this vulnerability.

    Fixed in 7.0.0-42.42.1~24.04.1
  38. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 7.0.0-42.42
  39. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 7.0.0-1016.17
  40. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 7.0.0-1016.18
  41. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 7.0.0-1017.17
  42. Upgrade

    Upgrade ubuntu/linux-oem-7.0 to a version that resolves this vulnerability.

    Fixed in 7.0.0-1017.17
  43. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 7.0.0-1015.16
  44. Upgrade

    Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.

    Fixed in 7.0.0-42.42.1
  45. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 5.10.271
  46. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 5.15.222
  47. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.1.189
  48. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.6.158
  49. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.12.112
  50. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.18.54
  51. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 7.2.8

Event History

Oct 6, 2026
CVE Published
via MITRE·08:46 AM
Data Sourced
via MITRE·08:46 AM
Description
Data Sourced
via OSV·09:18 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·09:18 AM
Description
Oct 7, 2026
Data Sourced
via Microsoft·08:46 AM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which deployments are affected by this issue?

The issue is relevant to systems using SRv6 End.DX4 IPIP decapsulation where packets arrive on an interface enslaved to a VRF. It affects IPv4 socket lookup behavior after decapsulation, particularly for traffic delivered to a local address.

2

What observable behavior indicates that a system is affected?

A UDP socket bound to the enslaved ingress interface may receive none of the decapsulated packets, while an unbound socket outside the VRF receives them. This violates the expected default VRF scoping for unbound UDP or TCP sockets.

3

Is a VRF required for the issue to occur?

The primary missing-flag behavior occurs when an SRv6 packet arrives through an interface enslaved to a VRF. With CONFIG_IPV6_MIP6 enabled, leftover frag_max_size state from a reassembled outer packet could also influence the flag without VRF involvement.

4

What change resolves the problem?

The resolution sets IPSKB_L3SLAVE from IP6SKB_L3SLAVE during IPv4 IPIP decapsulation in decap_and_validate(). This makes socket lookup handle the decapsulated packet as it would other traffic received through the VRF interface.

Contact

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