243 lines
14 KiB
JSON
243 lines
14 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-2026-97555",
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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": "2026-09-24T16:01:01.154Z",
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"datePublished": "2026-09-25T10:21:46.445Z",
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"dateUpdated": "2026-10-30T12:37:19.991Z"
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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": "2026-10-30T12:37:19.991Z"
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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\nsmb: client: fix heap overflow in DACL owner/group rewrite\n\nWhen id_mode_to_cifs_acl rewrites an existing DACL, it allocates a\nbuffer sized according to the on-disk DACL length reported by\ndacl_ptr->size. However, replace_sids_and_copy_aces may rewrite each\nACE with a new owner/group SID obtained from the cifs.idmap upcall.\nThose SIDs can have up to SID_MAX_SUB_AUTHORITIES (15) sub-authorities,\nmaking each ACE up to 76 bytes (sizeof(struct smb_ace)).\n\nIf the original DACL contains short SIDs (e.g., 1 sub-authority) while\nthe replacement SIDs are long, the rewritten ACEs overflow the\nallocation.\n\nFix this by always budgeting for worst-case SID expansion: allocate\nsizeof(struct smb_acl) plus num_aces * sizeof(struct smb_ace), which\ncovers the smb_acl header and room for every ACE at maximum SID size.\nThis replaces the previous split logic that used dacl_ptr->size for\ncifsacl mounts but num_aces * sizeof(struct smb_ace) for mode_from_sid\nmounts: both paths can trigger the same rewrite and need the same\nheadroom.\n\nKASAN reports this as:\n BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x1e8a/0x2680 [cifs]\n Write of size 4 at addr ffff8881a5e25374 by task chown/5298\n ...\n The buggy address is located 0 bytes to the right of\n allocated 884-byte region [ffff8881a5e25000, ffff8881a5e25374)"
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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:R/S:U/C:H/I:H/A:H",
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"baseScore": 8.8,
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"baseSeverity": "HIGH"
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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 - chown/chgrp reaches id_mode_to_cifs_acl via cifs_setattr_nounix, which fetches the NTSD through get_smb2_acl → SMB2_query_acl (SMB2 QUERY_INFO, InfoType=SMB2_O_INFO_SECURITY). The DACL that undersizes the kzalloc (dacl_ptr->size and short ACE SIDs) is that response body from a remote SMB server on TCP/445.\nAC:L - After setattr hits id_mode_to_cifs_acl's chown branch, overflow is deterministic: the server returns 1-sub-authority owner ACEs so dacl_ptr->size is compact, while idsfromsid builds a 3-sub-authority S-1-5-88 SID and id_to_sid() can return up to 15, and replace_sids_and_copy_aces/cifs_copy_ace writes the expanded ACEs with no race.\nPR:N - The attacker is the SMB server answering SMB2_query_acl on the existing tree-connect and holds no uid, share credential, or capability on the client. Local chown_ok/CAP_CHOWN belongs to the victim who issues chown/chgrp, not to the server.\nUI:R - The overflowing allocation is only in id_mode_to_cifs_acl's ATTR_UID/ATTR_GID (chown/chgrp) branch from cifs_setattr_nounix, so a user must chown(2) or chgrp(2) a file on a cifsacl, modefromsid, or posix_extensions CIFS mount of the attacker's share; lookup/stat/read never rewrite that DACL.\nS:U - The overflow is of the kmalloc'd pnntsd buffer inside id_mode_to_cifs_acl/build_sec_desc on the CIFS client host and stays in that kernel's own authority; it is not a VM, IOMMU, or sandbox escape.\nC:H - replace_sids_and_copy_aces heap-overflows pnntsd in build_sec_desc (KASAN slab-out-of-bounds write of expanded ACE/SID bytes). Corrupting neighboring slab objects is a kernel-memory disclosure primitive, so confidentiality is High.\nI:H - cifs_copy_ace writes server-chosen ACE type/flags/access_req and a longer SID past the end of id_mode_to_cifs_acl's kzalloc buffer, an out-of-bounds heap write that can corrupt adjacent objects and hijack control flow.\nA:H - The same out-of-bounds write in build_sec_desc was reported as KASAN slab-out-of-bounds by task chown and can oops or panic the client kernel, fully denying availability."
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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/smb/client/cifsacl.c"
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],
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"versions": [
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{
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"version": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "4e78b5ff13214353750b87283ff79f62510f5844",
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"status": "affected",
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"versionType": "git"
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},
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"version": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "63c2fbde15ffc9a0c21adf670c38d028e20fa65c",
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"status": "affected",
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},
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"lessThan": "d5cea6766ae1868a51c7d17d77d065b4f55c587f",
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"status": "affected",
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{
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"version": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1",
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"status": "affected",
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"versionType": "git"
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{
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"version": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "7fa84c9ca690643f429ae2709584a47e74b572c9",
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"status": "affected",
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"versionType": "git"
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{
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"version": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd",
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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": "bc3e9dd9d104ca1b75644eab87b38ce8a924aef4",
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"lessThan": "0ee150794c75bcd0be0e24ff3394f433cbae18cc",
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"status": "affected",
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"versionType": "git"
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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/smb/client/cifsacl.c"
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],
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"versions": [
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{
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"version": "5.12",
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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": "5.12",
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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": "5.15.224",
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"lessThanOrEqual": "5.15.*",
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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": "6.1.191",
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"lessThanOrEqual": "6.1.*",
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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": "6.6.158",
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"lessThanOrEqual": "6.6.*",
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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": "6.12.111",
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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": "6.18.53",
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"lessThanOrEqual": "6.18.*",
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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": "7.2.7",
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"lessThanOrEqual": "7.2.*",
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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": "7.3",
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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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"operator": "OR",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.12",
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/4e78b5ff13214353750b87283ff79f62510f5844"
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},
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{
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"url": "https://git.kernel.org/stable/c/63c2fbde15ffc9a0c21adf670c38d028e20fa65c"
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},
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{
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"url": "https://git.kernel.org/stable/c/d5cea6766ae1868a51c7d17d77d065b4f55c587f"
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},
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{
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"url": "https://git.kernel.org/stable/c/fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1"
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},
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{
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"url": "https://git.kernel.org/stable/c/7fa84c9ca690643f429ae2709584a47e74b572c9"
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},
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{
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"url": "https://git.kernel.org/stable/c/2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd"
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},
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{
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"url": "https://git.kernel.org/stable/c/0ee150794c75bcd0be0e24ff3394f433cbae18cc"
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}
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],
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"title": "smb: client: fix heap overflow in DACL owner/group rewrite",
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"x_generator": {
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} |