{"id":"CVE-2026-72421","title":"ipv4: fib: Don't ignore error route in local/main tables.","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fib: Don't ignore error route in local/main tables.\n\nWhen CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added,\nfib_lookup() performs route lookup directly o…","severity":"critical","cvss":10,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < a29e95fbc51e8a1b932773fd0e259b2080881443","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 5ae18d87a45698e8244d0fcba64c658c35a7dd3d","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 9127589aabdee588278e8d0d0bd3709a760a92c8","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 49eaf1403201357762d745a35882fb734107d763","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < fd25996f57a95d56bc568c89b4921edcf334b7d8","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 828fad4fd418bcdb9f5d66fec0d184c52a85ec31","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < a668fa160247d7bbe921548cb845f607b8b9305f","Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < b72f0db64205d9ce462038ba995d5d31eff32dc1","Linux 3.6"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T18:49:34.990573Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:55:23.102Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72421","references":[{"url":"https://git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443"},{"url":"https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d"},{"url":"https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8"},{"url":"https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763"},{"url":"https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8"},{"url":"https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31"},{"url":"https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f"},{"url":"https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1"}],"tags":["cve.org"],"epss":0.00595,"epssPercentile":0.47334,"ingestedAt":"2026-10-16T19:46:24.396Z","slug":"CVE-2026-72421","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fib: Don't ignore error route in local/main tables.\n\nWhen CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added,\nfib_lookup() performs route lookup directly on two tables.\n\nSince the first lookup does not properly bail out, the result\nof an error route in the merged local/main table could be\noverwritten by another route in the default table:\n\n  # unshare -n\n  # ip link set lo up\n  # ip route add 192.168.0.0/24 dev lo table 253\n  # ip route add unreachable 192.168.0.0/24\n  # ip route get 192.168.0.1\n  192.168.0.1 dev lo table default uid 0\n      cache <local>\n\nOnce a random rule is added, the error route is respected:\n\n  # ip rule add table 0\n  # ip rule del table 0\n  # ip route get 192.168.0.1\n  RTNETLINK answers: No route to host\n\nLet's fix the inconsistent behaviour.\n\n## Affected\n\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < a29e95fbc51e8a1b932773fd0e259b2080881443`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 5ae18d87a45698e8244d0fcba64c658c35a7dd3d`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 9127589aabdee588278e8d0d0bd3709a760a92c8`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 49eaf1403201357762d745a35882fb734107d763`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < fd25996f57a95d56bc568c89b4921edcf334b7d8`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < 828fad4fd418bcdb9f5d66fec0d184c52a85ec31`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < a668fa160247d7bbe921548cb845f607b8b9305f`\n- `Linux >= f4530fa574df4d833506c53697ed1daa0d390bf4 < b72f0db64205d9ce462038ba995d5d31eff32dc1`\n- `Linux 3.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":55,"depthScoreParts":{"impact":55,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}