{ "affected": [ { "ranges": [ { "events": [ { "introduced": "d5be7f632bad0f489879eed0ff4b99bd7fe0b74c" }, { "fixed": "5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c" }, { "fixed": "44378d02c5aaae24b60a75fbbb539b4aa4db503d" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "4.14.104" }, { "fixed": "4.15" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "4.19.26" }, { "fixed": "4.20" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "4.20.13" }, { "fixed": "4.21" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "4.14.226" }, { "fixed": "4.15" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "4.19.181" }, { "fixed": "4.20" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "dac7d4432b13d6b58923c1178b786bcda37c9e9e" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "e93384b12443c9bb6830b56b7d299beed432b865" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "f709f7b28d76de327373598a0fda9f916c36b5e6" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "d996573ebd5c528c613e90b7e7daa961d58fa16e" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "c375152be9dd9d6fbf6ae5ac8be337d0590f192a" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "0dab7eb86ea06ce8c530785f1999948c6f223c96" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" }, { "events": [ { "introduced": "54ef8243c3c8e90f1ea5792e6752e021a25c8eb3" } ], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "type": "GIT" } ] }, { "package": { "ecosystem": "Linux", "name": "Kernel" }, "ranges": [ { "events": [ { "introduced": "5.0.0" }, { "fixed": "7.2.11" } ], "type": "ECOSYSTEM" } ] } ], "database_specific": { "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98954.json" }, "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: always dissect GSO packets in __virtio_net_hdr_to_skb()\n\nCommit 9e8db5913264 (\"net: avoid false positives in untrusted gso\nvalidation\") added a '\u0026\u0026 skb-\u003enetwork_header' check before flow-dissecting\nGSO packets without VIRTIO_NET_HDR_F_NEEDS_CSUM in\n__virtio_net_hdr_to_skb(), because some callers (such as tun_get_user(),\ntun_xdp_one(), virtnet_receive_done(), and raw_verify_header()) called\nvirtio_net_hdr_*_to_skb() before initializing skb-\u003enetwork_header and\nskb-\u003edev.\n\nBecause __alloc_skb() and __build_skb_around() zero-initialize\nskb-\u003enetwork_header to 0 (unlike mac_header and transport_header which\nare initialized to ~0U), those four callers always had\nskb-\u003enetwork_header == 0 and bypassed flow dissection in\n__virtio_net_hdr_to_skb(). More generally, skb-\u003enetwork_header is an\noffset from skb-\u003ehead (where 0 is also a valid offset whenever\nskb_headroom(skb) is 0), not a boolean flag.\n\nWhenever the 'if (gso_type \u0026\u0026 skb-\u003enetwork_header)' branch was skipped,\nthe fallback 'else if (gso_type)' only pulled nh_min_len + thlen (40 bytes\nfor TCPv4) without dissecting the packet, without validating ip_proto or\nn_proto, and without setting skb-\u003etransport_header.\n\nIf the packet has a malformed network header, it is not rejected and a\nsubsequent skb_probe_transport_header() also fails, leaving\nskb-\u003etransport_header at ~0U (0xffff). Similarly, if an IPv4 packet\ncarries IP options (ihl \u003e 5) or an IPv6 packet carries extension headers,\npulling only nh_min_len + thlen can leave the TCP header outside\nskb-\u003ehead. In both cases, tcp_hdrlen(skb) in skb_gso_transport_seglen()\nreads out-of-bounds:\n\n BUG: KASAN: slab-out-of-bounds in skb_gso_transport_seglen\n Read of size 2 by task poc/133\n skb_gso_transport_seglen (net/core/gso.c:155)\n skb_gso_validate_mac_len (net/core/gso.c:270)\n tbf_enqueue (net/sched/sch_tbf.c:260)\n dev_qdisc_enqueue (net/core/dev.c:4227)\n __dev_queue_xmit (net/core/dev.c:4884)\n\nIn addition, checking virtio_net_hdr_match_proto() only inside\n'if (!skb-\u003eprotocol)' before flow dissection both skipped validation when\nskb-\u003eprotocol was pre-set by the caller and rejected VLAN-tagged frames\nwhose outer L2 protocol is ETH_P_8021Q or ETH_P_8021AD.\n\nFix this by:\n1. Initializing skb-\u003edev and skb-\u003enetwork_header (plus skb-\u003eprotocol for\n IFF_TUN) before virtio_net_hdr_*_to_skb() in tun_get_user(),\n tun_xdp_one(), virtnet_receive_done(), and raw_verify_header(). In\n tun_get_user(), drop the redundant skb_reset_mac_header(skb) in the\n IFF_TUN case since __virtio_net_hdr_to_skb() unconditionally resets\n mac_header.\n2. Removing '\u0026\u0026 skb-\u003enetwork_header' and the unvalidated\n 'else if (gso_type)' fallback in __virtio_net_hdr_to_skb() so all GSO\n packets without VIRTIO_NET_HDR_F_NEEDS_CSUM are flow-dissected, have\n their transport header pulled into linear data, and have\n skb-\u003etransport_header set.\n3. Moving the virtio_net_hdr_match_proto() check to after\n skb_flow_dissect_flow_keys_basic(), validating keys.basic.n_proto\n against hdr_gso_type.", "id": "CVE-2026-98954", "modified": "2026-10-28T02:30:28.149687838Z", "published": "2026-10-23T12:19:13.873Z", "references": [ { "type": "WEB", "url": "https://git.kernel.org/stable/c/44378d02c5aaae24b60a75fbbb539b4aa4db503d" }, { "type": "WEB", "url": "https://git.kernel.org/stable/c/5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c" }, { "type": "ADVISORY", "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98954.json" }, { "type": "ADVISORY", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98954" }, { "type": "PACKAGE", "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git" } ], "schema_version": "1.9.2", "summary": "net: always dissect GSO packets in __virtio_net_hdr_to_skb()" }