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vuln-cve/data/2026/74xxx/CVE-2026-74496.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-74496",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-08-15T05:44:03.906Z",
"datePublished": "2026-08-15T12:27:23.854Z",
"dateUpdated": "2026-10-16T19:05:50.395Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-03T10:56:03.355Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfou: Fix use-after-free in fou_create()\n\nfou_create() publishes struct fou through sk_user_data before adding the\nnew FOU port to the per-netns list. If fou_add_to_port_list() fails,\nthe error path frees fou while it is still reachable through\nsk_user_data. A concurrent receive can then dereference the freed\nobject in fou_from_sock().\n\nThis ordering issue was previously noted in the linked discussion.\n\nThe failure is reachable when local port 0 is requested. Each socket\nbinds to a different ephemeral port, but fou_cfg_cmp() compares the\nrequested port 0 and reports -EALREADY once an entry already exists.\n\nRelease the tunnel socket before freeing fou so sk_user_data is cleared\nfirst, and defer reclamation with kfree_rcu() to protect concurrent RCU\nreaders. This matches the lifetime handling in fou_release()."
}
],
"metrics": [
{
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"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The UAF is opened only via local FOU_CMD_ADD genetlink into fou_create(); remote UDP can race the dangling sk_user_data read in fou_udp_recv/gue_udp_recv but cannot alone reach the erroneous teardown path.\nAC:L - An attacker with CAP_NET_ADMIN controls both sides: issue a second FOU_CMD_ADD with port 0 to force -EALREADY on fou_add_to_port_list while concurrently sending UDP/GRO traffic to the just-bound ephemeral socket during the kfree window.\nPR:L - FOU_CMD_ADD is gated by GENL_ADMIN_PERM (CAP_NET_ADMIN); the fou genl family is netnsok, so a user with CAP_NET_ADMIN inside unshare -Urn can configure FOU and trigger the failing add path without init-namespace root.\nUI:N - Exploitation is fully programmatic via concurrent netlink FOU_CMD_ADD requests and attacker-controlled UDP packets; no victim mount, file open, or other interactive action is required.\nS:U - Impact is kernel heap corruption and privilege escalation within the same security authority; this is not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - Concurrent readers call fou_from_sock() and dereference freed struct fou fields (family, protocol, flags); reclaimed slab contents give attacker-controlled reads and kernel pointer disclosure primitives typical of UAF.\nI:H - Freed struct fou is attacker-reclaimable kmalloc memory; fou_gro_receive indexes inet_offloads[fou->protocol] from the dangling pointer, enabling heap grooming for arbitrary writes and control-flow hijack.\nA:H - Use-after-free in UDP receive/GRO softirq reliably causes KASAN violations and, on production kernels, invalid pointer dereferences or panics when accessing the freed fou object during packet processing."
}
]
}
],
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{
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"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/ipv4/fou_core.c"
],
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"lessThan": "0ee628a58d83e571f36ec9f07624d6845e420c50",
"status": "affected",
"versionType": "git"
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"version": "23461551c00628c3f3fe9cf837bf53cf8f212b63",
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"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
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],
"versions": [
{
"version": "3.18",
"status": "affected"
},
{
"version": "0",
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"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.10.271",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
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},
{
"version": "5.15.222",
"lessThanOrEqual": "5.15.*",
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},
{
"version": "6.1.189",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
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},
{
"version": "6.6.158",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
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},
{
"version": "6.12.111",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
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},
{
"version": "6.18.53",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
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},
{
"version": "7.1.8",
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
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},
{
"version": "7.2",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
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"operator": "OR",
"negate": false,
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"references": [
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"url": "https://git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50"
},
{
"url": "https://git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468"
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"url": "https://git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5"
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{
"url": "https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0"
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],
"title": "fou: Fix use-after-free in fou_create()",
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"adp": [
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"metrics": [
{
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"type": "ssvc",
"content": {
"id": "CVE-2026-74496",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-10-16T18:58:18.343359Z"
}
}
}
],
"title": "CISA ADP Vulnrichment",
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"dateUpdated": "2026-10-16T19:05:50.395Z"
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