CVE-2026-74684 (GCVE-0-2026-74684)
Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-25 05:41
VLAI
EPSS
VEX
Title
net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()
The commit 4f61f133f354 ("net: tap: NULL pointer derefence in
dev_parse_header_protocol when skb->dev is null") fixed a crash in
tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb().
This is required because virtio_net_hdr_to_skb() may invoke
dev_parse_header_protocol(), which dereferences skb->dev. Without the
assignment, a NULL pointer dereference can occur.
However, tap_get_user_xdp() still parses the virtio-net header before
assigning skb->dev. When the vhost TX path passes an XDP buffer containing
a GSO virtio-net header but the protocol is set to zero on purpose,
tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev
is still NULL, resulting in a crash.
Fix this by looking up the tap device and assigning skb->dev before calling
tun_vnet_hdr_to_skb(), matching the ordering already used in
tap_get_user(). Preserve the existing RCU read-side critical section across
dev_queue_xmit().
Severity
7.1 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
924a9bc362a5223cd448ca08c3dde21235adc310 , < 15583b07fd691a844fbf7b3ad612cdc9e9a657c0
(git)
Affected: 924a9bc362a5223cd448ca08c3dde21235adc310 , < 8b444b126cd8e4473e652f529753ed4dd1360a9c (git) Affected: 924a9bc362a5223cd448ca08c3dde21235adc310 , < 164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b (git) Affected: 924a9bc362a5223cd448ca08c3dde21235adc310 , < 3874892dd27d5387aa9a06f58d9060f18f351d24 (git) Affected: ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d (git) Affected: 54ef8243c3c8e90f1ea5792e6752e021a25c8eb3 (git) Affected: ca278267d6cd9544645731732455b6b20cb0e895 (git) Affected: faa3baa2828c5e1c4374f3e60041f75c64f5fcb6 (git) Affected: 99b1d3f74b9ef72c2f74c8e4c078e1bc0706e748 (git) Affected: 4.14.226 , < 4.15 (semver) Affected: 4.19.181 , < 4.20 (semver) Affected: 5.4.106 , < 5.5 (semver) Affected: 5.10.24 , < 5.11 (semver) Affected: 5.11.7 , < 5.12 (semver) |
guessed | |
| Linux | Linux |
Affected:
5.12
Unaffected: 0 , < 5.12 (semver) Unaffected: 6.12.105 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
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"programFiles": [
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"versions": [
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},
{
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"status": "unaffected",
"version": "0",
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},
{
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"version": "6.12.105",
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{
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"version": "6.18.45",
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{
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"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
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"vulnerable": true
},
{
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"versionStartIncluding": "5.12",
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},
{
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.4.106",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()\n\nThe commit 4f61f133f354 (\"net: tap: NULL pointer derefence in\ndev_parse_header_protocol when skb-\u003edev is null\") fixed a crash in\ntap_get_user() by assigning skb-\u003edev before calling tun_vnet_hdr_to_skb().\nThis is required because virtio_net_hdr_to_skb() may invoke\ndev_parse_header_protocol(), which dereferences skb-\u003edev. Without the\nassignment, a NULL pointer dereference can occur.\n\nHowever, tap_get_user_xdp() still parses the virtio-net header before\nassigning skb-\u003edev. When the vhost TX path passes an XDP buffer containing\na GSO virtio-net header but the protocol is set to zero on purpose,\ntun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb-\u003edev\nis still NULL, resulting in a crash.\n\nFix this by looking up the tap device and assigning skb-\u003edev before calling\ntun_vnet_hdr_to_skb(), matching the ordering already used in\ntap_get_user(). Preserve the existing RCU read-side critical section across\ndev_queue_xmit()."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - A malicious KVM guest reaches tap_get_user_xdp() by kicking the virtio-net TX virtqueue; vhost_net handle_tx_copy batches XDP buffers and invokes tap_sendmsg(TUN_MSG_PTR), not via any host network packet-receive path.\nAC:L - On typical QEMU/KVM vhost-net+tap/macvtap backends with TX batching enabled, a guest fully controls virtio-net GSO headers and Ethernet frames; sending GSO with ethertype 0 deterministically hits dev_parse_header_protocol() with skb-\u003edev NULL without races.\nPR:N - No host root or capabilities are required; a malicious cloud VM tenant only needs code execution inside a guest using virtio-net with a vhost-net tap backend, matching other guest-to-host virtio/KVM CNA scores.\nUI:N - No separate victim action is needed; the attacker submits crafted virtio-net TX descriptors from their own guest workload during normal VM operation without requiring host administrator interaction.\nS:C - Guest-supplied virtio-net TX data triggers a NULL pointer dereference in host tap_get_user_xdp(), panicking the physical host kernel and crossing the KVM guest-to-host virtualization security boundary.\nC:N - The failure mode is a NULL pointer dereference at dev-\u003eheader_ops with skb-\u003edev unset; there is no demonstrated out-of-bounds read, use-after-free, or other memory corruption that could disclose host kernel data.\nI:N - No guest-controlled host memory write or control-flow hijack occurs; the host kernel oopses on the NULL dereference before any exploitable modification beyond the immediate crash.\nA:H - The NULL pointer dereference in dev_parse_header_protocol() provokes a host kernel oops/panic in the vhost worker during guest virtio-net TX, denying availability of the hypervisor and all co-resident VMs."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:41:30.283Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0"
},
{
"url": "https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c"
},
{
"url": "https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b"
},
{
"url": "https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24"
}
],
"title": "net: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-74684",
"datePublished": "2026-08-22T15:32:50.846Z",
"dateReserved": "2026-08-15T05:44:03.926Z",
"dateUpdated": "2026-08-25T05:41:30.283Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-74684",
"date": "2026-10-09",
"epss": "0.00146",
"percentile": "0.03341"
},
"microsoft_vex": {
"current_release_date": "2026-09-23T02:27:10.000Z",
"cve": "CVE-2026-74684",
"id": "msrc_CVE-2026-74684",
"initial_release_date": "2026-08-24T01:08:47.000Z",
"product_status:known_affected": "2",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "net: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74684.json",
"version": "3"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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{
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"version": "99b1d3f74b9ef72c2f74c8e4c078e1bc0706e748",
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{
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"status": "affected",
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"version": "4.19.181",
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},
{
"lessThan": "5.5",
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"versionType": "semver"
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{
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{
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{
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"programFiles": [
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"versions": [
{
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},
{
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"status": "unaffected",
"version": "0",
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},
{
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"version": "6.18.45",
"versionType": "semver"
},
{
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"versionType": "semver"
},
{
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}
]
}
],
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}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()\n\nThe commit 4f61f133f354 (\"net: tap: NULL pointer derefence in\ndev_parse_header_protocol when skb-\u003edev is null\") fixed a crash in\ntap_get_user() by assigning skb-\u003edev before calling tun_vnet_hdr_to_skb().\nThis is required because virtio_net_hdr_to_skb() may invoke\ndev_parse_header_protocol(), which dereferences skb-\u003edev. Without the\nassignment, a NULL pointer dereference can occur.\n\nHowever, tap_get_user_xdp() still parses the virtio-net header before\nassigning skb-\u003edev. When the vhost TX path passes an XDP buffer containing\na GSO virtio-net header but the protocol is set to zero on purpose,\ntun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb-\u003edev\nis still NULL, resulting in a crash.\n\nFix this by looking up the tap device and assigning skb-\u003edev before calling\ntun_vnet_hdr_to_skb(), matching the ordering already used in\ntap_get_user(). Preserve the existing RCU read-side critical section across\ndev_queue_xmit()."
}
],
"id": "CVE-2026-74684",
"lastModified": "2026-08-25T06:18:51.253",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.5,
"impactScore": 4.0,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-22T16:16:42.757",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-25T08:54:11+00:00",
"cve": "CVE-2026-74684",
"id": "CVE-2026-74684",
"initial_release_date": "2026-08-22T00:00:00+00:00",
"product_status:known_affected": "232",
"product_status:known_not_affected": "42",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74684.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-10-08T17:01:15Z",
"cve": "CVE-2026-74684",
"id": "CVE-2026-74684",
"initial_release_date": "2026-08-25T01:19:18Z",
"product_status:known_affected": "68",
"product_status:known_not_affected": "89",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-74684",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-74684.json",
"version": "10"
}
}
}
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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