138 lines
7.9 KiB
JSON
138 lines
7.9 KiB
JSON
{
|
|
"dataType": "CVE_RECORD",
|
|
"dataVersion": "5.2",
|
|
"cveMetadata": {
|
|
"cveId": "CVE-2026-89695",
|
|
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
|
|
"state": "PUBLISHED",
|
|
"assignerShortName": "Linux",
|
|
"dateReserved": "2026-09-11T19:38:34.750Z",
|
|
"datePublished": "2026-09-11T19:46:14.258Z",
|
|
"dateUpdated": "2026-10-19T08:51:08.488Z"
|
|
},
|
|
"containers": {
|
|
"cna": {
|
|
"providerMetadata": {
|
|
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
|
|
"shortName": "Linux",
|
|
"dateUpdated": "2026-10-19T08:51:08.488Z"
|
|
},
|
|
"descriptions": [
|
|
{
|
|
"lang": "en",
|
|
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cap decoded POSIX ACL count to bound sort cost\n\nnfsd4_decode_posixacl() reads a u32 entry count off the wire and passes\nit straight to posix_acl_alloc() and sort_pacl_range(). The latter is\nan O(n^2) bubble sort, so a client-chosen count drives unbounded CPU in\nthe server's compound processing path.\n\n nfsd4_decode_posixacl()\n xdr_stream_decode_u32(&count) /* uncapped u32 */\n posix_acl_alloc(count, GFP_KERNEL)\n sort_pacl_range(*acl, 0, count - 1) /* O(n^2) bubble sort */\n\nThe encoder side in the same file already rejects ACLs whose a_count\nexceeds NFS_ACL_MAX_ENTRIES, but the decoder introduced in commit\n5fc51dfc2eb1 (\"NFSD: Add support for XDR decoding POSIX draft ACLs\")\nomitted the symmetric check.\n\nFix by rejecting a wire count greater than NFS_ACL_MAX_ENTRIES with\nnfserr_inval, before any allocation, so the sort is bounded by\nNFS_ACL_MAX_ENTRIES^2 comparisons.\n\nWhile we're in here, also fix the nfserr_resource return if\nposix_acl_alloc() fails. That's not a legal error code for v4.1+. Change\nit to return nfserr_jukebox as that's more appropriate for memory\nallocation failures."
|
|
}
|
|
],
|
|
"metrics": [
|
|
{
|
|
"cvssV3_1": {
|
|
"version": "3.1",
|
|
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
|
|
"baseScore": 7.5,
|
|
"baseSeverity": "HIGH"
|
|
},
|
|
"scenarios": [
|
|
{
|
|
"lang": "en",
|
|
"value": "AV:N - The flaw is in nfsd's NFSv4 XDR decoder (nfsd4_decode_posixacl in fs/nfsd/nfs4xdr.c), reached when a remote client sends COMPOUND SETATTR, CREATE, or OPEN with POSIX draft ACL fattrs over TCP/2049.\nAC:L - The attacker supplies the u32 ACL count and reverse-sorted ACE payload on the wire; decode then runs sort_pacl_range() deterministically with no race, victim state, or memory-layout dependency.\nPR:N - nfsd4_decode_posixacl() runs during COMPOUND XDR decode before SEQUENCE, filehandle, export, or setattr checks; under AUTH_SYS, the common NFS flavor, RPC credentials are attacker-asserted and no secret is verified.\nUI:N - nfsd worker threads decode and sort the attacker's COMPOUND automatically; no local user or administrator action is required.\nS:U - Impact stays inside the host kernel's nfsd thread pool; this is not a VM escape, IOMMU bypass, or other cross-authority boundary.\nC:N - The bug only burns CPU while sorting a temporary decoded POSIX ACL; it does not read kernel or file contents, and a failed posix_acl_alloc() returns an NFS error without leaking memory.\nI:N - sort_pacl_range() only reorders the attacker's own temporary ACL buffer, which is discarded on error; no kernel memory is corrupted and no on-disk ACL is applied without later authorization.\nA:H - A client-chosen ACE count, practically hundreds of thousands within the 4MiB RPC payload, drives an un-preempted O(n^2) bubble sort in an nfsd thread, stalling the finite nfsd pool so repeated requests fully deny NFS service."
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"affected": [
|
|
{
|
|
"product": "Linux",
|
|
"vendor": "Linux",
|
|
"defaultStatus": "unaffected",
|
|
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
|
|
"programFiles": [
|
|
"fs/nfsd/nfs4xdr.c"
|
|
],
|
|
"versions": [
|
|
{
|
|
"version": "5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05",
|
|
"lessThan": "ea14d71d6ecb925673761bcf79f781f7dc9042cc",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
},
|
|
{
|
|
"version": "5fc51dfc2eb160bd7ab3251ab1767cacf9c8bf05",
|
|
"lessThan": "4bc1108e876153a2dd6d874052b99182c3603135",
|
|
"status": "affected",
|
|
"versionType": "git"
|
|
}
|
|
]
|
|
},
|
|
{
|
|
"product": "Linux",
|
|
"vendor": "Linux",
|
|
"defaultStatus": "affected",
|
|
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
|
|
"programFiles": [
|
|
"fs/nfsd/nfs4xdr.c"
|
|
],
|
|
"versions": [
|
|
{
|
|
"version": "7.0",
|
|
"status": "affected"
|
|
},
|
|
{
|
|
"version": "0",
|
|
"lessThan": "7.0",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "7.2.4",
|
|
"lessThanOrEqual": "7.2.*",
|
|
"status": "unaffected",
|
|
"versionType": "semver"
|
|
},
|
|
{
|
|
"version": "7.3",
|
|
"lessThanOrEqual": "*",
|
|
"status": "unaffected",
|
|
"versionType": "original_commit_for_fix"
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"cpeApplicability": [
|
|
{
|
|
"nodes": [
|
|
{
|
|
"operator": "OR",
|
|
"negate": false,
|
|
"cpeMatch": [
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "7.0",
|
|
"versionEndExcluding": "7.2.4"
|
|
},
|
|
{
|
|
"vulnerable": true,
|
|
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
|
|
"versionStartIncluding": "7.0",
|
|
"versionEndExcluding": "7.3"
|
|
}
|
|
]
|
|
}
|
|
]
|
|
}
|
|
],
|
|
"references": [
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/ea14d71d6ecb925673761bcf79f781f7dc9042cc"
|
|
},
|
|
{
|
|
"url": "https://git.kernel.org/stable/c/4bc1108e876153a2dd6d874052b99182c3603135"
|
|
}
|
|
],
|
|
"title": "nfsd: cap decoded POSIX ACL count to bound sort cost",
|
|
"x_generator": {
|
|
"engine": "bippy-1.2.0"
|
|
}
|
|
}
|
|
}
|
|
} |