{"api_version":"1","generated_at":"2026-11-08T16:02:59+00:00","cve":"CVE-2026-98954","urls":{"html":"https://cve.report/CVE-2026-98954","api":"https://cve.report/api/cve/CVE-2026-98954.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98954","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98954"},"summary":{"title":"net: always dissect GSO packets in __virtio_net_hdr_to_skb()","description":"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 '&& skb->network_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->network_header and\nskb->dev.\n\nBecause __alloc_skb() and __build_skb_around() zero-initialize\nskb->network_header to 0 (unlike mac_header and transport_header which\nare initialized to ~0U), those four callers always had\nskb->network_header == 0 and bypassed flow dissection in\n__virtio_net_hdr_to_skb(). More generally, skb->network_header is an\noffset from skb->head (where 0 is also a valid offset whenever\nskb_headroom(skb) is 0), not a boolean flag.\n\nWhenever the 'if (gso_type && skb->network_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->transport_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->transport_header at ~0U (0xffff). Similarly, if an IPv4 packet\ncarries IP options (ihl > 5) or an IPv6 packet carries extension headers,\npulling only nh_min_len + thlen can leave the TCP header outside\nskb->head. 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->protocol)' before flow dissection both skipped validation when\nskb->protocol 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->dev and skb->network_header (plus skb->protocol 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 '&& skb->network_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->transport_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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-23 13:17:16","updated_at":"2026-10-23 13:17:16"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/44378d02c5aaae24b60a75fbbb539b4aa4db503d","name":"https://git.kernel.org/stable/c/44378d02c5aaae24b60a75fbbb539b4aa4db503d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c","name":"https://git.kernel.org/stable/c/5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98954","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98954","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d5be7f632bad0f489879eed0ff4b99bd7fe0b74c 5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d5be7f632bad0f489879eed0ff4b99bd7fe0b74c 44378d02c5aaae24b60a75fbbb539b4aa4db503d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dac7d4432b13d6b58923c1178b786bcda37c9e9e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e93384b12443c9bb6830b56b7d299beed432b865 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f709f7b28d76de327373598a0fda9f916c36b5e6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d996573ebd5c528c613e90b7e7daa961d58fa16e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c375152be9dd9d6fbf6ae5ac8be337d0590f192a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0dab7eb86ea06ce8c530785f1999948c6f223c96 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 54ef8243c3c8e90f1ea5792e6752e021a25c8eb3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.14.104 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.19.26 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.20.13 4.21 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.14.226 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.19.181 4.20 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.11 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["arch/um/drivers/vector_transports.c","drivers/net/tun.c","drivers/net/virtio_net.c","include/linux/virtio_net.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c","status":"affected","version":"d5be7f632bad0f489879eed0ff4b99bd7fe0b74c","versionType":"git"},{"lessThan":"44378d02c5aaae24b60a75fbbb539b4aa4db503d","status":"affected","version":"d5be7f632bad0f489879eed0ff4b99bd7fe0b74c","versionType":"git"},{"status":"affected","version":"dac7d4432b13d6b58923c1178b786bcda37c9e9e","versionType":"git"},{"status":"affected","version":"e93384b12443c9bb6830b56b7d299beed432b865","versionType":"git"},{"status":"affected","version":"f709f7b28d76de327373598a0fda9f916c36b5e6","versionType":"git"},{"status":"affected","version":"d996573ebd5c528c613e90b7e7daa961d58fa16e","versionType":"git"},{"status":"affected","version":"c375152be9dd9d6fbf6ae5ac8be337d0590f192a","versionType":"git"},{"status":"affected","version":"0dab7eb86ea06ce8c530785f1999948c6f223c96","versionType":"git"},{"status":"affected","version":"ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d","versionType":"git"},{"status":"affected","version":"54ef8243c3c8e90f1ea5792e6752e021a25c8eb3","versionType":"git"},{"lessThan":"4.15","status":"affected","version":"4.14.104","versionType":"semver"},{"lessThan":"4.20","status":"affected","version":"4.19.26","versionType":"semver"},{"lessThan":"4.21","status":"affected","version":"4.20.13","versionType":"semver"},{"lessThan":"4.15","status":"affected","version":"4.14.226","versionType":"semver"},{"lessThan":"4.20","status":"affected","version":"4.19.181","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["arch/um/drivers/vector_transports.c","drivers/net/tun.c","drivers/net/virtio_net.c","include/linux/virtio_net.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.0"},{"lessThan":"5.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.11","versionStartIncluding":"5.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"5.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.104","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.26","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.104","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.26","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.20.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.226","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.181","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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 '&& skb->network_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->network_header and\nskb->dev.\n\nBecause __alloc_skb() and __build_skb_around() zero-initialize\nskb->network_header to 0 (unlike mac_header and transport_header which\nare initialized to ~0U), those four callers always had\nskb->network_header == 0 and bypassed flow dissection in\n__virtio_net_hdr_to_skb(). More generally, skb->network_header is an\noffset from skb->head (where 0 is also a valid offset whenever\nskb_headroom(skb) is 0), not a boolean flag.\n\nWhenever the 'if (gso_type && skb->network_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->transport_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->transport_header at ~0U (0xffff). Similarly, if an IPv4 packet\ncarries IP options (ihl > 5) or an IPv6 packet carries extension headers,\npulling only nh_min_len + thlen can leave the TCP header outside\nskb->head. 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->protocol)' before flow dissection both skipped validation when\nskb->protocol 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->dev and skb->network_header (plus skb->protocol 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 '&& skb->network_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->transport_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."}],"providerMetadata":{"dateUpdated":"2026-10-23T12:19:13.873Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/5f4dfdf0077730e9d3ef5b37ceb17a5a56d6f34c"},{"url":"https://git.kernel.org/stable/c/44378d02c5aaae24b60a75fbbb539b4aa4db503d"}],"title":"net: always dissect GSO packets in __virtio_net_hdr_to_skb()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98954","datePublished":"2026-10-23T12:19:13.873Z","dateReserved":"2026-09-25T10:25:14.382Z","dateUpdated":"2026-10-23T12:19:13.873Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-23 13:17:16","lastModifiedDate":"2026-10-23 13:17:16","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98954","Ordinal":"1","Title":"net: always dissect GSO packets in __virtio_net_hdr_to_skb()","CVE":"CVE-2026-98954","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98954","Ordinal":"1","NoteData":"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 '&& skb->network_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->network_header and\nskb->dev.\n\nBecause __alloc_skb() and __build_skb_around() zero-initialize\nskb->network_header to 0 (unlike mac_header and transport_header which\nare initialized to ~0U), those four callers always had\nskb->network_header == 0 and bypassed flow dissection in\n__virtio_net_hdr_to_skb(). More generally, skb->network_header is an\noffset from skb->head (where 0 is also a valid offset whenever\nskb_headroom(skb) is 0), not a boolean flag.\n\nWhenever the 'if (gso_type && skb->network_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->transport_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->transport_header at ~0U (0xffff). Similarly, if an IPv4 packet\ncarries IP options (ihl > 5) or an IPv6 packet carries extension headers,\npulling only nh_min_len + thlen can leave the TCP header outside\nskb->head. 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->protocol)' before flow dissection both skipped validation when\nskb->protocol 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->dev and skb->network_header (plus skb->protocol 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 '&& skb->network_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->transport_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.","Type":"Description","Title":"net: always dissect GSO packets in __virtio_net_hdr_to_skb()"}]}}}