289 lines
16 KiB
JSON
289 lines
16 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-2026-53390",
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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": "2026-06-09T07:44:35.402Z",
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"datePublished": "2026-07-19T12:01:54.951Z",
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"dateUpdated": "2026-08-17T04:50:41.549Z"
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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": "2026-08-17T04:50:41.549Z"
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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\nksmbd: fix out-of-bounds read in smb_check_perm_dacl()\n\nThe permission-check ACE walk in smb_check_perm_dacl() validates the ACE\nheader size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it\nnever checks that ace->size is actually large enough to contain\nnum_subauth sub-authorities before compare_sids() dereferences them.\n\nCIFS_SID_BASE_SIZE covers the SID header up to but excluding the\nsub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header,\nso the existing guards only guarantee the 8-byte SID base, i.e. zero\nsub-authorities. compare_sids() then reads ace->sid.sub_auth[i] for\ni < min(local_sid->num_subauth, ace->sid.num_subauth). The local\ncomparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid()\nresult) always have at least one sub-authority, and an attacker controls\nthe ACE revision and authority bytes (which lie within the in-bounds SID\nbase), so they can match one of those SIDs and force the sub_auth read.\n\nA crafted ACE with size == 16 and num_subauth >= 1 placed at the tail of\nthe security descriptor therefore causes a heap out-of-bounds read of up\nto SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd\nallocation. The security descriptor is loaded by ksmbd_vfs_get_sd_xattr()\ninto a buffer sized exactly to the on-disk data (kzalloc(sd_size) in\nndr_decode_v4_ntacl()), so the read lands past the allocation. The\nmalformed descriptor can be stored verbatim via SMB2_SET_INFO (the DACL\nis not normalised before being written to the security.NTACL xattr) and\nthe read fires on a subsequent SMB2_CREATE access check, making this\nreachable by an authenticated client on a share that uses ACL xattrs.\n\nAdd the missing num_subauth-versus-ace_size check, mirroring the\nidentical guards already present in the sibling parsers parse_dacl() and\nsmb_inherit_dacl()."
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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:L/UI:N/S:U/C:H/I:N/A:H",
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"baseScore": 8.1,
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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 - The bug is reachable through ksmbd's in-kernel SMB2 server on TCP/445 via SMB2_SET_INFO (to store a crafted security descriptor) and SMB2_CREATE (to trigger the DACL walk), with packets handled from ksmbd_conn_handler_loop() through smb2_set_info()/smb2_open() into smb_check_perm_dacl().\nAC:L - An attacker fully controls the malformed ACE fields (size, num_subauth, revision, authority bytes) and can reliably place the ACE at the tail of a security descriptor, store it verbatim, then trigger the read on the next CREATE without depending on race timing or uncontrollable memory layout.\nPR:L - Exploitation requires a completed SMB2 session and share access: SMB2_SET_INFO needs FILE_WRITE_DAC/FILE_WRITE_OWNER on an open file, and the poisoned descriptor is only persisted on shares with ACL xattr support, which is authenticated low-privilege client access rather than pre-auth or host root.\nUI:N - No end-user action is required beyond the attacker sending crafted SMB2 protocol messages over the network; no victim must open a file, mount a share, or perform any interactive step.\nS:U - The vulnerability is confined to kernel heap memory reads during ksmbd DACL permission evaluation and does not cross a security boundary such as guest-to-host VM escape or sandbox escape.\nC:H - compare_sids() performs a heap out-of-bounds read of up to SID_MAX_SUB_AUTHORITIES (15) sub-authority dwords (60 bytes) past the kzalloc()-sized security descriptor buffer, exposing adjacent kernel heap contents even though the data is not returned in the SMB response.\nI:N - The flaw is a read-only out-of-bounds access in compare_sids() with no memory write, type confusion, or demonstrated control-flow hijack primitive; integrity is not directly compromised.\nA:H - Reading past the end of the kmalloc allocation can fault the kernel (oops/panic), and a malicious descriptor planted on a shared file can deny availability to any other authenticated client whose SMB2_CREATE triggers smb_check_perm_dacl()."
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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/server/smbacl.c"
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],
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"versions": [
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{
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"version": "282cbbb476b9f35793452bc461934af4c7eca169",
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"lessThan": "c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0",
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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": "f20adc4ef7428bc485ee83fd1a592252fb87718b",
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"lessThan": "988c93d3bba066d8669143e6ec30bb2be9608d53",
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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": "325d4ac11f526cb8964cff14548ccf02d8c756d8",
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"lessThan": "36599894fa8536fefdf1e296c0af71b8b7226859",
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"status": "affected",
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},
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"lessThan": "d5c81a095c86fe507c032d08f3a8cfc518444927",
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"status": "affected",
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"versionType": "git"
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},
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{
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"lessThan": "7627ff8c4f9919f14de562b0160ab4ec9d80b1f7",
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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": "d07b26f39246a82399661936dd0c853983cfade7",
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"lessThan": "e36e35660adb9b8ef1435ac359151dda5f094c55",
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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": "d07b26f39246a82399661936dd0c853983cfade7",
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"lessThan": "1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b",
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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": "151b1799861fde38087c08f613abc2843ef597b0",
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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": "5.15.210",
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"lessThan": "5.15.212",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "6.1.176",
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"lessThan": "6.1.177",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "6.6.140",
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"lessThan": "6.6.144",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "6.12.84",
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"lessThan": "6.12.95",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "6.18.25",
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"lessThan": "6.18.38",
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"status": "affected",
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"versionType": "semver"
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},
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{
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"version": "7.0.2",
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"lessThan": "7.1",
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"status": "affected",
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"versionType": "semver"
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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/server/smbacl.c"
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],
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"versions": [
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{
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"version": "7.1",
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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": "7.1",
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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": "5.15.212",
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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": "6.1.177",
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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": "6.6.144",
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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": "6.12.95",
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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": "6.18.38",
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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": "7.1.3",
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"lessThanOrEqual": "7.1.*",
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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": "7.2",
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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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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.15.210",
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0"
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},
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{
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"url": "https://git.kernel.org/stable/c/988c93d3bba066d8669143e6ec30bb2be9608d53"
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},
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{
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"url": "https://git.kernel.org/stable/c/36599894fa8536fefdf1e296c0af71b8b7226859"
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},
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{
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"url": "https://git.kernel.org/stable/c/d5c81a095c86fe507c032d08f3a8cfc518444927"
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},
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{
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"url": "https://git.kernel.org/stable/c/7627ff8c4f9919f14de562b0160ab4ec9d80b1f7"
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},
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{
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"url": "https://git.kernel.org/stable/c/e36e35660adb9b8ef1435ac359151dda5f094c55"
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},
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{
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"url": "https://git.kernel.org/stable/c/1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b"
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}
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],
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"title": "ksmbd: fix out-of-bounds read in smb_check_perm_dacl()",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |