{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80590", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.770Z", "datePublished": "2026-08-28T06:35:12.516Z", "dateUpdated": "2026-10-19T08:43:12.426Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:43:12.426Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ninet: frags: strip GSO state from fragments before reassembly\n\nA virtio_net_hdr (tun/tap, or AF_PACKET with PACKET_VNET_HDR) can mark\nan IPv4 or IPv6 fragment as GSO; nothing relates gso_type to frag_off.\ninet_frag_reasm_prepare()/inet_frag_reasm_finish() keep the first\nfragment's skb as the head of the reassembled datagram, including its\nshinfo->gso_size/gso_type/gso_segs, and chain the remaining fragments\non frag_list with whatever linear/paged layout they arrived with.\n\nAfter ip_defrag() (ip_local_deliver(), nf_defrag_ipv4, ...) the\nreassembled skb therefore still claims to be GSO (SKB_GSO_DODGY), and\nthe next software segmentation point - udp_rcv_segment() on local\ndelivery, validate_xmit_skb(), or the ip_finish_output_gso() slow\npath - hands it to skb_segment(). skb_segment()'s frag_list walk\nassumes GRO-shaped input and hits one of its BUG_ON()s. Two writes to\na tap by an unprivileged user in its own userns are enough:\n\n kernel BUG at net/core/skbuff.c:4899!\n Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n CPU: 0 UID: 1000 PID: 82 Comm: poc Not tainted 7.2.0-pentest+ #2\n RIP: 0010:skb_segment+0x20ca/0x48b0\n Call Trace:\n \n __udp_gso_segment+0x29a/0x27d0\n udp4_ufo_fragment+0x458/0x6c0\n inet_gso_segment+0x429/0x1340\n skb_mac_gso_segment+0x233/0x4f0\n __skb_gso_segment+0x308/0x660\n udp_queue_rcv_skb+0x440/0xad0\n udp_unicast_rcv_skb+0xc7/0x2c0\n udp_rcv+0x16ce/0x2260\n ip_protocol_deliver_rcu+0x197/0x2d0\n ip_local_deliver+0x430/0x690\n ip_rcv+0x16f/0x1f0\n __netif_receive_skb_one_core+0x15e/0x1c0\n __netif_receive_skb+0x1e/0x110\n netif_receive_skb+0xf6/0x5c0\n tun_rx_batched.isra.0+0x3ab/0x790\n tun_get_user+0x17c3/0x3550\n tun_chr_write_iter+0xba/0x1b0\n vfs_write+0x646/0x1130\n \n Kernel panic - not syncing: Fatal exception in interrupt\n\nThis runs with BH disabled, so it is a panic rather than an oops. The\nsame is reachable with CAP_NET_RAW in a netns where a defrag point\nprecedes a GSO point, and from a guest whose VMM forwards\nvirtio_net_hdr to a tap. The SKB_GSO_DODGY frag_list checks added by\ncommit 3dcbdb134f32 (\"net: gso: Fix skb_segment splat when splitting\ngso_size mangled skb having linear-headed frag_list\") and by\ncommit 9e4b7a99a03a (\"net: gso: fix panic on frag_list with mixed head\nalloc types\") do not cover it: page-backed heads skip them, and kmalloc\nheads skip them when gso_size == skb_headlen(head), which the sender\ncontrols.\n\nAn skb entering a frag queue is an IP fragment by definition and\ncannot legitimately carry GSO state: GRO does not merge fragments and\nthe stack segments before it fragments, so only untrusted sources are\naffected. This has been reachable since\ncommit f43798c27684 (\"tun: Allow GSO using virtio_net_hdr\"), the first\npath that let userspace attach GSO metadata to an IP fragment. Reset\nthe GSO fields of every fragment as it is queued, in\ninet_frag_queue_insert(), which IPv4, IPv6, nf_conntrack_reasm and\n6lowpan reassembly share; then neither the head nor the frag_list\nmembers of the reassembled skb carry them (the members matter too:\nthe ip_do_fragment()/ip6_fragment() fast paths send them out as they\nare). The head may remain CHECKSUM_PARTIAL; that is already accepted\non receive and resolved by skb_checksum_help() in\nip_do_fragment()/ip6_fragment() on forward.\n\nTested on top of net.git (dc4b95b8fee9), x86_64: the tap reproducer\nabove, two further IPv4 frag_list geometries that reach\nBUG_ON(i >= nfrags) and BUG_ON(!list_skb->head_frag), and an IPv6\nfragment-header variant (udp6_ufo_fragment()) each panic the unpatched\nkernel; with this patch all four datagrams are delivered intact and\nnothing is logged." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "baseScore": 8.6, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - A malicious cloud VM guest injects virtio_net_hdr-marked IPv4/IPv6 fragments through virtio-net/vhost-tap into the host ip_rcv() path; the same inet_frag reassembly and skb_segment() crash also fires on validate_xmit_skb()/ip_finish_output_gso() when such skbs traverse forwarding.\nAC:L - The attacker fully controls virtio_net_hdr gso_type/gso_size and fragment geometry; the commit reproduces a host panic from two tap writes with no races, timing, or uncontrollable memory layout required.\nPR:N - On typical KVM/QEMU tap-backed virtio-net deployments a tenant VM needs no host account or capability; exploitation uses only the pre-provisioned virtual NIC, not init-namespace root or CAP_NET_ADMIN on the host.\nUI:N - Packet injection, ip_defrag reassembly, and GSO segmentation run automatically in softirq once crafted virtio fragments are sent; no victim mount, click, or other cooperative action is required.\nS:C - A guest VM tenant can panic the host kernel by crossing the hypervisor virtio/tap boundary, impacting resources outside the guest security authority even though the demonstrated primitive is denial of service rather than full escape.\nC:N - Impact is an intentional BUG_ON in skb_segment() frag_list handling; there is no demonstrated out-of-bounds read, use-after-free, or other information-disclosure primitive before the assertion aborts.\nI:N - The failure aborts in skb_segment() before any out-of-bounds write, page-desc conversion, or control-flow hijack; attacker-controlled metadata only reaches a defensive assertion, not a memory modification primitive.\nA:H - Triggering skb_segment() BUG_ON from tun_rx/tun_get_user runs with BH disabled and causes a fatal kernel panic, fully and repeatedly denying availability of the affected host until reboot." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/inet_fragment.c" ], "versions": [ { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "cfdbc8c2e6f9ef5d8b8e54859da03dfe682b0bee", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "29dda278a5ed272f2230ff4eaa23cf403107bba0", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "14a8f3e10fa9a5abd6cedcdaa0c0b7ea9a09f234", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "3edf721bb4b99d272c336631b44e3d8ff9a4f31b", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "dec2edb7aaf12a8878b3a03172ea8fc277b8eaad", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "c49f04e8d2b94dbb8d9fd99731dd3f00589c8ace", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "69b73b74d9eb45f5560a8fe4fa406ada580e1340", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "da857e448322a2e871ce3ecc2900027041160d43", "status": "affected", "versionType": "git" }, { "version": "f43798c27684ab925adde7d8acc34c78c6e50df8", "lessThan": "d5dc1e69fd7258ea605c9952e5d5947539159ae3", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/inet_fragment.c" ], "versions": [ { "version": "2.6.27", "status": "affected" }, { "version": "0", "lessThan": "2.6.27", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.268", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.219", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.186", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.155", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.107", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.48", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.12", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.2", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "5.10.268" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "5.15.219" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "6.1.186" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "6.6.155" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "6.12.107" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "6.18.48" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "7.1.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "7.2.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.27", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/cfdbc8c2e6f9ef5d8b8e54859da03dfe682b0bee" }, { "url": "https://git.kernel.org/stable/c/29dda278a5ed272f2230ff4eaa23cf403107bba0" }, { "url": "https://git.kernel.org/stable/c/14a8f3e10fa9a5abd6cedcdaa0c0b7ea9a09f234" }, { "url": "https://git.kernel.org/stable/c/3edf721bb4b99d272c336631b44e3d8ff9a4f31b" }, { "url": "https://git.kernel.org/stable/c/dec2edb7aaf12a8878b3a03172ea8fc277b8eaad" }, { "url": "https://git.kernel.org/stable/c/c49f04e8d2b94dbb8d9fd99731dd3f00589c8ace" }, { "url": "https://git.kernel.org/stable/c/69b73b74d9eb45f5560a8fe4fa406ada580e1340" }, { "url": "https://git.kernel.org/stable/c/da857e448322a2e871ce3ecc2900027041160d43" }, { "url": "https://git.kernel.org/stable/c/d5dc1e69fd7258ea605c9952e5d5947539159ae3" } ], "title": "inet: frags: strip GSO state from fragments before reassembly", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-80590", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:18:13.413771Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:29.280Z" } } ] } }