CVE-2026-80905 (GCVE-0-2026-80905)
Vulnerability from cvelistv5 – Published: 2026-09-04 17:19 – Updated: 2026-09-04 17:19
VLAI
EPSS
VEX
Title
net: tap: fix wrong transport_header when sending VLAN-tagged frame
Summary
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. 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.
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
8c76e77f9069f10505c08e02646c3ee11ad79038 , < 5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b
(git)
Affected: 8c76e77f9069f10505c08e02646c3ee11ad79038 , < 88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3 (git) Affected: 8c76e77f9069f10505c08e02646c3ee11ad79038 , < cbb35cbe8db268fefe34c23df15348cf99025298 (git) Affected: 3cae5ef1f37a475faf7c40bc6a3c170779f3e0b1 (git) Affected: 4.20.1 , < 4.21 (semver) |
guessed | |
| Linux | Linux |
Affected:
5.0
Unaffected: 0 , < 5.0 (semver) Unaffected: 6.18.46 , ≤ 6.18.* (semver) Unaffected: 7.1.10 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/tap.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b",
"status": "affected",
"version": "8c76e77f9069f10505c08e02646c3ee11ad79038",
"versionType": "git"
},
{
"lessThan": "88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3",
"status": "affected",
"version": "8c76e77f9069f10505c08e02646c3ee11ad79038",
"versionType": "git"
},
{
"lessThan": "cbb35cbe8db268fefe34c23df15348cf99025298",
"status": "affected",
"version": "8c76e77f9069f10505c08e02646c3ee11ad79038",
"versionType": "git"
},
{
"status": "affected",
"version": "3cae5ef1f37a475faf7c40bc6a3c170779f3e0b1",
"versionType": "git"
},
{
"lessThan": "4.21",
"status": "affected",
"version": "4.20.1",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/tap.c"
],
"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": "6.18.*",
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.46",
"versionStartIncluding": "5.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.10",
"versionStartIncluding": "5.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "4.20.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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-\u003eprotocol 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."
}
],
"providerMetadata": {
"dateUpdated": "2026-09-04T17:19:15.289Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b"
},
{
"url": "https://git.kernel.org/stable/c/88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3"
},
{
"url": "https://git.kernel.org/stable/c/cbb35cbe8db268fefe34c23df15348cf99025298"
}
],
"title": "net: tap: fix wrong transport_header when sending VLAN-tagged frame",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-80905",
"datePublished": "2026-09-04T17:19:15.289Z",
"dateReserved": "2026-08-26T14:34:25.800Z",
"dateUpdated": "2026-09-04T17:19:15.289Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-80905\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-04T18:18:00.120\",\"lastModified\":\"2026-09-04T18:18:00.120\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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-\u003eprotocol 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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/net/tap.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"8c76e77f9069f10505c08e02646c3ee11ad79038\",\"lessThan\":\"5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8c76e77f9069f10505c08e02646c3ee11ad79038\",\"lessThan\":\"88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8c76e77f9069f10505c08e02646c3ee11ad79038\",\"lessThan\":\"cbb35cbe8db268fefe34c23df15348cf99025298\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"3cae5ef1f37a475faf7c40bc6a3c170779f3e0b1\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"4.20.1\",\"lessThan\":\"4.21\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/net/tap.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.0\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.0\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.46\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.10\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cbb35cbe8db268fefe34c23df15348cf99025298\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-05T00:24:44Z",
"cve": "CVE-2026-80905",
"id": "CVE-2026-80905",
"initial_release_date": "2026-09-05T00:24:44Z",
"product_status:known_affected": "260",
"product_status:known_not_affected": "93",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-80905",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80905.json",
"version": "2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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