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Vulnerability · Published Apr 24, 2026 · Assigned by Linux

CVE-2026-31668seg6: separate dst_cache for input and output paths in seg6 lwtunnel

Critical 9.8

In plain English

A critical-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.4%top 61.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: seg6: separate dst_cache for input and output paths in seg6 lwtunnel The seg6 lwtunnel uses a single dst_cache per encap route, shared between seg6_input_core() and seg6_output_core(). These two paths can perform the post-encap SID lookup in different routing contexts (e.g., ip rules matching on the ingress interface, or VRF table separation). Whichever path runs first populates the cache, and the other reuses it blindly, bypassing its own lookup. Fix this by splitting the cache into cache_input and cache_output, so each path maintains its own cached dst independently.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.170-1DEBIAN-CVE-2026-31668
Debian:13linux6.12.85-1DEBIAN-CVE-2026-31668
Debian:14linux6.19.13-1DEBIAN-CVE-2026-31668
Ubuntu:22.04:LTSlinux5.15.0-185.195UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux5.15.0-185.195USN-8493-1
Ubuntu:24.04:LTSlinux6.8.0-134.134UBUNTU-CVE-2026-31668
Ubuntu:25.10linux6.17.0-40.40USN-8490-1
Ubuntu:25.10linux6.17.0-40.40UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-aws5.15.0-1111.118USN-8493-1
Ubuntu:22.04:LTSlinux-aws5.15.0-1111.118UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-aws6.8.0-1060.63UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-aws6.17.0-1019.19USN-8490-1
Ubuntu:25.10linux-aws6.17.0-1019.19UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1USN-8490-1
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1060.63~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure5.15.0-1116.125USN-8493-1
Ubuntu:22.04:LTSlinux-azure5.15.0-1116.125UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure6.8.0-1063.71UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1021.21~24.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1063.71~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1116.125UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1062.69UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1062.69~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gcp5.15.0-1111.121UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gcp5.15.0-1111.121USN-8493-1
Ubuntu:24.04:LTSlinux-gcp6.8.0-1063.69UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-gcp6.17.0-1020.22UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-gcp6.17.0-1020.22USN-8490-1
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1USN-8490-1
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1063.69~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gke5.15.0-1107.113UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gke5.15.0-1107.113USN-8493-1
Ubuntu:24.04:LTSlinux-gke6.8.0-1058.64UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1094.102USN-8493-1
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1094.102UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1045.48UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1USN-8545-1
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-136.136~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-ibm5.15.0-1105.109USN-8493-1
Ubuntu:22.04:LTSlinux-ibm5.15.0-1105.109UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-ibm6.8.0-1060.61UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1060.61~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1106.112UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1106.112USN-8493-1
Ubuntu:22.04:LTSlinux-kvm5.15.0-1103.108USN-8493-1
Ubuntu:22.04:LTSlinux-kvm5.15.0-1103.108UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-183.193UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-183.193USN-8493-1
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-134.134.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-134.134.1~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1106.107UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1106.107USN-8493-1
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1058.61UBUNTU-CVE-2026-31668
Ubuntu:26.04:LTSlinux-nvidia7.0.0-1006.6UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1026.26USN-8508-1
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1026.26UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1058.61~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1058.61.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1063.63UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1063.63USN-8493-1
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1029.30UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1052.52UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1052.52USN-8493-1
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28USN-8491-1
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oracle5.15.0-1108.114UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oracle5.15.0-1108.114USN-8493-1
Ubuntu:24.04:LTSlinux-oracle6.8.0-1057.58UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-oracle6.17.0-1018.18UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-oracle6.17.0-1018.18USN-8490-1
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1USN-8490-1
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1057.58~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-raspi5.15.0-1105.108USN-8527-1
Ubuntu:22.04:LTSlinux-raspi5.15.0-1105.108UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-raspi6.8.0-1060.64UBUNTU-CVE-2026-31668
Ubuntu:25.10linux-raspi6.17.0-1021.21USN-8546-1
Ubuntu:25.10linux-raspi6.17.0-1021.21UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-31668
Ubuntu:25.10linux-realtime6.17.0-1017.19USN-8490-2
Ubuntu:25.10linux-realtime6.17.0-1017.19UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-31668
Ubuntu:25.10linux-riscv6.17.0-40.40.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-134.134~22.04.1UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-31668
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1032.33UBUNTU-CVE-2026-31668
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1074.78USN-8528-1
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1074.78UBUNTU-CVE-2026-31668

Affected products (as reported)

VendorProductVersions
Linux Linux 6c8702c60b88651072460f3f4026c7dfe2521d12 – before 1dec91d3b1cefb82635761b7812154af3ef464496c8702c60b88651072460f3f4026c7dfe2521d12 – before 750569d6987a0ff46317a4b86eb3907e296287bf6c8702c60b88651072460f3f4026c7dfe2521d12 – before 57d0374d14fa667dec6952173b93e7e84486d5c96c8702c60b88651072460f3f4026c7dfe2521d12 – before 84d458018b147176b259347103fccb7e93abd2b16c8702c60b88651072460f3f4026c7dfe2521d12 – before 6305ad032b03d2ea4181b953a66e19a9a6ed053c6c8702c60b88651072460f3f4026c7dfe2521d12 – before fb56de5d99218de49d5d43ef3a99e062ecd0f9a16c8702c60b88651072460f3f4026c7dfe2521d12 – before 17d87d42874f5d6c1a0ccc6d9190dfe82a9a7a6a6c8702c60b88651072460f3f4026c7dfe2521d12 – before c3812651b522fe8437ebb7063b75ddb95b571643
Linux Linux 4.10

Weakness: CWE-459 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References