CVE-2026-80905
In the Linux kernel, the following vulnerability has been resolved:
net: tap: fix wrong transport_header when sending VLAN-tagged frame
In tap_get_user_xdp(), when processing a VLAN-tagged frame (e.g. ETH_P_8021Q), skb_set_network_header() is called first to advance network_header past the VLAN tag to the inner protocol header. skb_probe_transport_header() is then called with skb->protocol still set to ETH_P_8021Q, while nhoff (derived from skb_network_offset()) already points past the VLAN tag to the inner protocol header.
In __skb_flow_dissect(), proto is initialized to ETH_P_8021Q and nhoff points past the VLAN tag.
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When the dissector hits case ETH_P_8021Q, it reads a struct vlan_hdr at the current nhoff via __skb_header_pointer(), but that offset contains the inner protocol header (e.g. an IP header). The bytes are misinterpreted as a VLAN header, yielding a garbage encapsulated EtherType that matches no known protocol. The dissector returns false, so skb_probe_transport_header() never calls skb_set_transport_header(), leaving transport_header at its uninitialized sentinel value (~0U).
Move skb_set_network_header() to after skb_probe_transport_header(). At the time skb_probe_transport_header() is called, network_header still points to the VLAN header (offset ETH_HLEN), so nhoff is correct and the flow dissector can parse the VLAN header, extract the inner EtherType, and advance nhoff to the inner protocol header, allowing transport_header to be set correctly.
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-80905",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
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"vendor": "Linux",
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{
"status": "affected",
"version": "8c76e77f9069f10505c08e02646c3ee11ad79038",
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{
"status": "affected",
"version": "4.20.1",
"lessThan": "4.21",
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}
],
"programFiles": [
"drivers/net/tap.c"
],
"defaultStatus": "unaffected"
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{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
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{
"status": "affected",
"version": "5.0"
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{
"status": "unaffected",
"version": "0",
"lessThan": "5.0",
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{
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
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{
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
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{
"status": "unaffected",
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"versionType": "original_commit_for_fix",
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],
"published": "2026-09-04T18:18:00.120",
"references": [
{
"url": "https://git.kernel.org/stable/c/5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tap: fix wrong transport_header when sending VLAN-tagged frame\n\nIn tap_get_user_xdp(), when processing a VLAN-tagged frame (e.g.\nETH_P_8021Q), skb_set_network_header() is called first to advance\nnetwork_header past the VLAN tag to the inner protocol header.\nskb_probe_transport_header() is then called with skb->protocol still\nset to ETH_P_8021Q, while nhoff (derived from skb_network_offset())\nalready points past the VLAN tag to the inner protocol header.\n\nIn __skb_flow_dissect(), proto is initialized to ETH_P_8021Q and nhoff\npoints past the VLAN tag. When the dissector hits case ETH_P_8021Q, it\nreads a struct vlan_hdr at the current nhoff via __skb_header_pointer(),\nbut that offset contains the inner protocol header (e.g. an IP header).\nThe bytes are misinterpreted as a VLAN header, yielding a garbage\nencapsulated EtherType that matches no known protocol. The dissector\nreturns false, so skb_probe_transport_header() never calls\nskb_set_transport_header(), leaving transport_header at its uninitialized\nsentinel value (~0U).\n\nMove skb_set_network_header() to after skb_probe_transport_header(). At\nthe time skb_probe_transport_header() is called, network_header still\npoints to the VLAN header (offset ETH_HLEN), so nhoff is correct and the\nflow dissector can parse the VLAN header, extract the inner EtherType,\nand advance nhoff to the inner protocol header, allowing transport_header\nto be set correctly."
}
],
"lastModified": "2026-09-04T18:18:00.120",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}