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Vulnerability · Published Aug 15, 2026 · Assigned by Linux

CVE-2026-72421ipv4: fib: Don't ignore error route in local/main tables.

Critical 10.0

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 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)10.0Critical
Exploit odds (30 days)0.6%top 52.6% 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: ipv4: fib: Don't ignore error route in local/main tables. When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added, fib_lookup() performs route lookup directly on two tables. Since the first lookup does not properly bail out, the result of an error route in the merged local/main table could be overwritten by another route in the default table: # unshare -n # ip link set lo up # ip route add 192.168.0.0/24 dev lo table 253 # ip route add unreachable 192.168.0.0/24 # ip route get 192.168.0.1 192.168.0.1 dev lo table default uid 0 cache <local> Once a random rule is added, the error route is respected: # ip rule add table 0 # ip rule del table 0 # ip route get 192.168.0.1 RTNETLINK answers: No route to host Let's fix the inconsistent behaviour.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.180-1DEBIAN-CVE-2026-72421
Debian:13linux6.12.100-1DEBIAN-CVE-2026-72421
Debian:14linux7.1.5-1DEBIAN-CVE-2026-72421
Ubuntu:22.04:LTSlinux5.15.0-198.208UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux6.8.0-147.147UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux7.0.0-38.38UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-aws5.15.0-1117.124UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-aws6.8.0-1067.70UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-aws7.0.0-1014.14UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-aws-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure5.15.0-1123.132UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure6.8.0-1071.79UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-azure7.0.0-1017.17UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1017.17~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1122.131UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1069.76UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1016.16UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1016.16~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gcp5.15.0-1118.128UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gcp6.8.0-1071.79UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-gcp7.0.0-1014.14UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gke5.15.0-1113.119UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gke6.8.0-1066.74UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-gke7.0.0-1008.9UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1100.108UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1052.56UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-38.38~24.04.4UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-ibm5.15.0-1111.115UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-ibm6.8.0-1067.68UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-ibm7.0.0-1015.15UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1112.118UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-kvm5.15.0-1109.114UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-195.205UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-147.147.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1112.113UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1024.25~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2022.23UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1070.72UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1035.38UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1059.59UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1015.15UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oracle5.15.0-1114.120UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oracle6.8.0-1064.67UBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-oracle7.0.0-1013.13UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-realtime7.0.0-38.38.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-72421
Ubuntu:26.04:LTSlinux-riscv7.0.0-38.38.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-38.38.1~24.04.1UBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-72421
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-72421
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1080.84UBUNTU-CVE-2026-72421

Affected products (as reported)

VendorProductVersions
Linux Linux f4530fa574df4d833506c53697ed1daa0d390bf4 – before a29e95fbc51e8a1b932773fd0e259b2080881443f4530fa574df4d833506c53697ed1daa0d390bf4 – before 5ae18d87a45698e8244d0fcba64c658c35a7dd3df4530fa574df4d833506c53697ed1daa0d390bf4 – before 9127589aabdee588278e8d0d0bd3709a760a92c8f4530fa574df4d833506c53697ed1daa0d390bf4 – before 49eaf1403201357762d745a35882fb734107d763f4530fa574df4d833506c53697ed1daa0d390bf4 – before fd25996f57a95d56bc568c89b4921edcf334b7d8f4530fa574df4d833506c53697ed1daa0d390bf4 – before 828fad4fd418bcdb9f5d66fec0d184c52a85ec31f4530fa574df4d833506c53697ed1daa0d390bf4 – before a668fa160247d7bbe921548cb845f607b8b9305ff4530fa574df4d833506c53697ed1daa0d390bf4 – before b72f0db64205d9ce462038ba995d5d31eff32dc1
Linux Linux 3.6

References