CVE-2026-90037 (GCVE-0-2026-90037)
Vulnerability from cvelistv5 – Published: 2026-09-16 10:33 – Updated: 2026-10-30 12:33
VLAI
EPSS
VEX
Title
NFSD: Prevent client use-after-free during close_lru reaping
Summary
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Prevent client use-after-free during close_lru reaping
An nfs4_openowner left on nn->close_lru after its final CLOSE keeps
its last closed stateid in oo_last_closed_stid, holding only a raw
pointer to its nfs4_client. The laundromat reaps timed-out entries,
drops nn->client_lock, and calls nfs4_put_stid(), which dereferences
the client through cl_lock. Nothing pins the client across that
window, so a concurrent force_expire_client() can free it and
nfs4_put_stid() reads freed memory. __destroy_client() hits the same
race, walking clp->cl_openowners without cl_lock.
Pin the client with cl_rpc_users before dropping client_lock, and
skip clients already expiring. __destroy_client() then cleans up its
own close_lru entries through release_last_closed_stateid(), so
teardown no longer races the laundromat.
Severity
9.8 (Critical)
Assigner
References
6 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
217526e7ecc9f6f243e976772e81eab7ab986a4c , < 1d721729762a413015864b2a56d7fb86fb8efa9f
(git)
Affected: 217526e7ecc9f6f243e976772e81eab7ab986a4c , < adc34b5df5c5d87043cb500b0867fc1c4ad0117e (git) Affected: 217526e7ecc9f6f243e976772e81eab7ab986a4c , < 0763482227822f7343557f086afc382086d56c4c (git) Affected: 217526e7ecc9f6f243e976772e81eab7ab986a4c , < 83dd59ac1c3455c2c7d8ddb582d980a13199b9b3 (git) Affected: 217526e7ecc9f6f243e976772e81eab7ab986a4c , < e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1 (git) Affected: 217526e7ecc9f6f243e976772e81eab7ab986a4c , < 2330b788d732f43668b965b3105b37ceb276dfea (git) |
guessed | |
| Linux | Linux |
Affected:
3.17
Unaffected: 0 , < 3.17 (semver) Unaffected: 6.1.191 , ≤ 6.1.* (semver) Unaffected: 6.6.160 , ≤ 6.6.* (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.51 , ≤ 6.18.* (semver) Unaffected: 7.2.5 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix) |
guessed |
{
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"product": "Linux",
"programFiles": [
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"version": "3.17"
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"version": "0",
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{
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"version": "6.6.160",
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{
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"status": "unaffected",
"version": "6.12.111",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.51",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.191",
"versionStartIncluding": "3.17",
"vulnerable": true
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{
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{
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.5",
"versionStartIncluding": "3.17",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "3.17",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
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}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during close_lru reaping\n\nAn nfs4_openowner left on nn-\u003eclose_lru after its final CLOSE keeps\nits last closed stateid in oo_last_closed_stid, holding only a raw\npointer to its nfs4_client. The laundromat reaps timed-out entries,\ndrops nn-\u003eclient_lock, and calls nfs4_put_stid(), which dereferences\nthe client through cl_lock. Nothing pins the client across that\nwindow, so a concurrent force_expire_client() can free it and\nnfs4_put_stid() reads freed memory. __destroy_client() hits the same\nrace, walking clp-\u003ecl_openowners without cl_lock.\n\nPin the client with cl_rpc_users before dropping client_lock, and\nskip clients already expiring. __destroy_client() then cleans up its\nown close_lru entries through release_last_closed_stateid(), so\nteardown no longer races the laundromat."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - nfsd is the in-kernel NFS server. A remote NFSv4.0 client reaches the UAF over TCP/UDP 2049: CLOSE places the openowner on nn-\u003eclose_lru, and SETCLIENTID_CONFIRM (ALLOWED_WITHOUT_FH) calls expire_client() while nfs4_laundromat() drops client_lock and nfs4_put_stid() uses the unpinned nfs4_client.\nAC:L - The attacker drives both sides: OPEN/CLOSE compounds fill close_lru so the laundromat drops client_lock once per nfs4_put_stid(), and concurrent SETCLIENTID_CONFIRM with matching AUTH_SYS creds replaces the client via expire_client(). FATTR4_LEASE_TIME times the window; flooding close_lru widens it; the race is retryable.\nPR:N - Typical nfsd deployments use AUTH_SYS/AUTH_NULL, so RPC uids are self-asserted. SETCLIENTID and SETCLIENTID_CONFIRM are ALLOWED_WITHOUT_FH; any host allowed by the export can OPEN/CLOSE and replace the client with no local account or capability on the NFS server.\nUI:N - The attacker issues the NFSv4.0 compounds (SETCLIENTID, OPEN, CLOSE, RENEW, SETCLIENTID_CONFIRM) itself. No administrator or other user on the victim server must mount a filesystem, write nfsdfs ctl, or otherwise interact.\nS:U - The use-after-free is of the nfsd nfs4_client object (client_slab) in the NFS server kernel. Impact stays in that kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - After free_client() kmem_cache_free()s the nfs4_client, nfs4_put_stid() still reads cl_lock and cl_stateids. Reclaiming the mergeable client_slab object via further SETCLIENTID discloses kernel heap; a UAF is C:H.\nI:H - nfs4_put_stid() then takes cl_lock and idr_remove()s from cl_stateids on the freed nfs4_client, a slab UAF write concurrent with __destroy_client(). Heap reuse enables arbitrary write and control-flow hijack; a UAF is I:H.\nA:H - Use-after-free of nfs4_client in nfs4_put_stid() (spin_lock of freed cl_lock) oopses or panics the nfsd laundromat worker even without a full exploit, denying service of the NFS server host."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:33:53.924Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/1d721729762a413015864b2a56d7fb86fb8efa9f"
},
{
"url": "https://git.kernel.org/stable/c/adc34b5df5c5d87043cb500b0867fc1c4ad0117e"
},
{
"url": "https://git.kernel.org/stable/c/0763482227822f7343557f086afc382086d56c4c"
},
{
"url": "https://git.kernel.org/stable/c/83dd59ac1c3455c2c7d8ddb582d980a13199b9b3"
},
{
"url": "https://git.kernel.org/stable/c/e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1"
},
{
"url": "https://git.kernel.org/stable/c/2330b788d732f43668b965b3105b37ceb276dfea"
}
],
"title": "NFSD: Prevent client use-after-free during close_lru reaping",
"x_generator": {
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}
}
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-90037",
"datePublished": "2026-09-16T10:33:36.673Z",
"dateReserved": "2026-09-11T19:38:34.782Z",
"dateUpdated": "2026-10-30T12:33:53.924Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-90037",
"date": "2026-11-09",
"epss": "0.00514",
"percentile": "0.44077"
},
"microsoft_vex": {
"current_release_date": "2026-11-07T01:50:56.000Z",
"cve": "CVE-2026-90037",
"id": "msrc_CVE-2026-90037",
"initial_release_date": "2026-09-17T01:13:28.000Z",
"product_status:fixed": "1",
"product_status:known_affected": "4",
"product_status:under_investigation": "1",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "NFSD: Prevent client use-after-free during close_lru reaping",
"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-90037.json",
"version": "8"
},
"nvd": {
"cve": {
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{
"affectedData": [
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"product": "Linux",
"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
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"versionType": "git"
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.17"
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{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
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{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.191",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.160",
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{
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"version": "6.12.111",
"versionType": "semver"
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{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.51",
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{
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"lessThanOrEqual": "*",
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}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during close_lru reaping\n\nAn nfs4_openowner left on nn-\u003eclose_lru after its final CLOSE keeps\nits last closed stateid in oo_last_closed_stid, holding only a raw\npointer to its nfs4_client. The laundromat reaps timed-out entries,\ndrops nn-\u003eclient_lock, and calls nfs4_put_stid(), which dereferences\nthe client through cl_lock. Nothing pins the client across that\nwindow, so a concurrent force_expire_client() can free it and\nnfs4_put_stid() reads freed memory. __destroy_client() hits the same\nrace, walking clp-\u003ecl_openowners without cl_lock.\n\nPin the client with cl_rpc_users before dropping client_lock, and\nskip clients already expiring. __destroy_client() then cleans up its\nown close_lru entries through release_last_closed_stateid(), so\nteardown no longer races the laundromat."
}
],
"id": "CVE-2026-90037",
"lastModified": "2026-10-30T13:20:39.433",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-09-16T11:17:16.910",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0763482227822f7343557f086afc382086d56c4c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1d721729762a413015864b2a56d7fb86fb8efa9f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2330b788d732f43668b965b3105b37ceb276dfea"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/83dd59ac1c3455c2c7d8ddb582d980a13199b9b3"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/adc34b5df5c5d87043cb500b0867fc1c4ad0117e"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e57a9ed34ea8c17e831de59b8f1a6b2d80d347a1"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-11-06T01:28:27+00:00",
"cve": "CVE-2026-90037",
"id": "CVE-2026-90037",
"initial_release_date": "2026-09-16T00:00:00+00:00",
"product_status:known_affected": "203",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: NFSD: Prevent client use-after-free during close_lru reaping",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90037.json",
"version": "3"
}
}
}
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
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Related by attack behaviour
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