159 lines
8.8 KiB
JSON
159 lines
8.8 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2025-40212",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2025-04-16T07:20:57.179Z",
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"datePublished": "2025-11-24T13:04:20.888Z",
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"dateUpdated": "2026-08-05T12:08:37.417Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-05T12:08:37.417Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix refcount leak in nfsd_set_fh_dentry()\n\nnfsd exports a \"pseudo root filesystem\" which is used by NFSv4 to find\nthe various exported filesystems using LOOKUP requests from a known root\nfilehandle. NFSv3 uses the MOUNT protocol to find those exported\nfilesystems and so is not given access to the pseudo root filesystem.\n\nIf a v3 (or v2) client uses a filehandle from that filesystem,\nnfsd_set_fh_dentry() will report an error, but still stores the export\nin \"struct svc_fh\" even though it also drops the reference (exp_put()).\nThis means that when fh_put() is called an extra reference will be dropped\nwhich can lead to use-after-free and possible denial of service.\n\nNormal NFS usage will not provide a pseudo-root filehandle to a v3\nclient. This bug can only be triggered by the client synthesising an\nincorrect filehandle.\n\nTo fix this we move the assignments to the svc_fh later, after all\npossible error cases have been detected."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 9.8,
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"baseSeverity": "CRITICAL"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - The bug is in the in-kernel NFS server (nfsd) and is triggered by a crafted filehandle sent by a remote NFSv3/v2 client over the network (TCP/UDP port 2049).\nAC:L - The attacker fully controls the synthesized filehandle and triggers the double exp_put deterministically with a single request; the required V4ROOT pseudo-root export exists by default whenever NFSv4 is enabled, and no race is involved.\nPR:N - NFS clients are unauthenticated at the network level (AUTH_SYS/AUTH_NULL merely assert an identity), and the bug requires no OS privileges on the server — a malicious client simply synthesizes an invalid pseudo-root filehandle.\nUI:N - Exploitation requires only that the attacker send a crafted NFSv3 request; no action by any local user or administrator is needed.\nS:U - The use-after-free is confined to the kernel's own memory/security authority with no crossing of a trust boundary such as a VM or IOMMU.\nC:H - The over-released svc_export becomes a use-after-free object; per UAF scoring the attacker can gain control over freed/reallocated memory contents, enabling arbitrary kernel information disclosure.\nI:H - A use-after-free of a heap object (svc_export) enables heap grooming and write primitives against the reallocated memory, supporting kernel integrity compromise and control-flow hijacking.\nA:H - The premature free of an in-use svc_export reliably causes use-after-free crashes/oops, and repeated requests can drive the refcount underflow to panic the server."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/nfsd/nfsfh.c"
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],
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"versions": [
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{
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"version": "ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444",
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"lessThan": "b6bc86ce3944b10b9fc181fc00c1a520a20ed965",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444",
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"lessThan": "c83d7365cec5eb5ebeeee2a72e29b4ca58a7e4c2",
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"status": "affected",
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},
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{
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"lessThan": "8a7348a9ed70bda1c1f51d3f1815bcbdf9f3b38c",
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"status": "affected",
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/nfsd/nfsfh.c"
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],
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"versions": [
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{
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"version": "6.12",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.12",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.59",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.17.9",
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"lessThanOrEqual": "6.17.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.12",
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"versionEndExcluding": "6.12.59"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.12",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/b6bc86ce3944b10b9fc181fc00c1a520a20ed965"
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},
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{
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"url": "https://git.kernel.org/stable/c/c83d7365cec5eb5ebeeee2a72e29b4ca58a7e4c2"
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},
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{
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"url": "https://git.kernel.org/stable/c/8a7348a9ed70bda1c1f51d3f1815bcbdf9f3b38c"
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}
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],
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"title": "nfsd: fix refcount leak in nfsd_set_fh_dentry()",
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