{"cve":"CVE-2026-53012","nvd":{"published":"2026-06-24T17:17:12.433","modified":"2026-10-15T02:20:00.860","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: fix IPv6 route referencing IPv4 nexthop\n\nsyzbot reported a panic [1] [2].\n\nWhen an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag\nof all groups containing this nexthop is not updated. This is because\nnh_group_v4_update is only called when replacing AF_INET to AF_INET6,\nbut the reverse direction (AF_INET6 to AF_INET) is missed.\n\nThis allows a stale has_v4=false to bypass fib6_check_nexthop, causing\nIPv6 routes to be attached to groups that effectively contain only AF_INET\nmembers. Subsequent route lookups then call nexthop_fib6_nh() which\nreturns NULL for the AF_INET member, leading to a NULL pointer\ndereference.\n\nFix by calling nh_group_v4_update whenever the family changes, not just\nAF_INET to AF_INET6.\n\nReproducer:\n\t# AF_INET6 blackhole\n\tip -6 nexthop add id 1 blackhole\n\t# group with has_v4=false\n\tip nexthop add id 100 group 1\n\t# replace with AF_INET (no -6), has_v4 stays false\n\tip nexthop replace id 1 blackhole\n\t# pass stale has_v4 check\n\tip -6 route add 2001:db8::/64 nhid 100\n\t# panic\n\tping -6 2001:db8::1\n\n[1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0\n[2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/29c95185ba32b621fbc3800fb86e7dc3edf5c2be","https://git.kernel.org/stable/c/613c8f4a501421dd258b07ea614205d4e16ec845","https://git.kernel.org/stable/c/6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8","https://git.kernel.org/stable/c/9c2d6770a5f4545a307eb66979bef7656a34d621","https://git.kernel.org/stable/c/aaac3bed034239e1d75732211d9b05f30b0b4f35"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:41:17.107060303+00:00"},"epss":{"cve":"CVE-2026-53012","score":0.00137,"percentile":0.03066,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}