{"id":"CVE-2026-98955","revision":"03d771901f3a4493a4797d595d80904c","records":[{"revision":"03d771901f3a4493a4797d595d80904c","observedAt":"2026-10-23T16:01:20.601+00:00","statement":{"source":"cve-program","id":"CVE-2026-98955","aliases":[],"title":"flow_dissector: avoid u16 truncation of skb->len when computing thoff","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: avoid u16 truncation of skb->len when computing thoff\n\n__skb_flow_dissect() computes key_control->thoff using:\n\n  key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen);\n\nmin_t(u16, ...) casts both arguments to u16 before comparing them.\nWhenever skb->len (or hlen) modulo 65536 is smaller than nhoff, the\ntruncated length wins and thoff is set to a bogus small value, even\nwhen the dissection succeeded. For example, an IPv4/TCP frame with\nskb->len == 65540 and nhoff == 34 gets thoff == 4, so callers such as\nskb_probe_transport_header() point the transport header inside the\nEthernet header.\n\nSuch skbs are not exotic:\n- At the time of commit d0c081b49137 (\"flow_dissector: properly cap\n  thoff field\"), AF_PACKET with PACKET_VNET_HDR could already build GSO\n  skbs larger than 64KB (MTU checks are skipped for GSO, and\n  alloc_skb_with_frags() accepted up to MAX_SKB_FRAGS (17) order-0\n  pages on top of the linear part).\n- BIG TCP now makes skbs larger than 64KB common.\n- The following patch makes tun_get_user() dissect IFF_TAP frames\n  before eth_type_trans() pulls the Ethernet header, so a GSO frame\n  carrying a 65522..65535 byte L3 packet will be dissected with\n  skb->len in [65536, 65549].\n\nCompare as u32 instead. If the resulting offset cannot be represented\nin the u16 key_control->thoff, cap it to U16_MAX and report the\ndissection as failed rather than silently returning a wrong transport\noffset. thoff is still set on failure, as some callers (such as\neth_get_headlen()) use it regardless of the return value.","state":0,"publishedAt":"2026-10-23T12:19:15.287+00:00","modifiedAt":"2026-10-23T12:19:15.287+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/core/flow_dissector.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"d0c081b49137cd3200f2023c0875723be66e7ce5\",\n                            \"lessThan\": \"d9e08836d06c84abb18470c94b12b131eaccdc7d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d0c081b49137cd3200f2023c0875723be66e7ce5\",\n                            \"lessThan\": \"50d0cd575cab763f833d6ac6eb6550b23a0b3dae\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d0c081b49137cd3200f2023c0875723be66e7ce5\",\n                            \"lessThan\": \"9993e6a0ac1b5b3101ffba702cacb9f42b9909d8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d0c081b49137cd3200f2023c0875723be66e7ce5\",\n                            \"lessThan\": \"52efce4755a4b8b82039caa773645ffc80b25362\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d0c081b49137cd3200f2023c0875723be66e7ce5\",\n                            \"lessThan\": \"99bda1ecbd56905f8bd934b9cdccd3bd251192b1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d35cd5e279881ec36ff8cd82a2d9caebc0cce3fc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"eecfa2eeefe3caef4c8d6b2284f6066c76ab26a1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"80f327285cab6ab8e10c3ea03278add5dd99fb02\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"4.4.114\",\n                            \"lessThan\": \"4.5\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"4.9.79\",\n                            \"lessThan\": \"4.10\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"4.14.16\",\n                            \"lessThan\": \"4.15\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/core/flow_dissector.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.15\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.15\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.160\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.113\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.57\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.11\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/d9e08836d06c84abb18470c94b12b131eaccdc7d","https://git.kernel.org/stable/c/50d0cd575cab763f833d6ac6eb6550b23a0b3dae","https://git.kernel.org/stable/c/9993e6a0ac1b5b3101ffba702cacb9f42b9909d8","https://git.kernel.org/stable/c/52efce4755a4b8b82039caa773645ffc80b25362","https://git.kernel.org/stable/c/99bda1ecbd56905f8bd934b9cdccd3bd251192b1"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98955","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98955","identifiers":["CVE-2026-98955"]},"retained":false,"historicalAffected":[]}],"coverage":[]}