264 lines
15 KiB
JSON
264 lines
15 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-2026-97926",
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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": "2026-09-25T10:18:58.203Z",
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"datePublished": "2026-09-25T10:22:44.197Z",
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"dateUpdated": "2026-10-19T09:10:53.241Z"
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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": "2026-10-19T09:10:53.241Z"
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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\nufs: validate cylinder group metadata before caching it\n\nufs_read_cylinder() copies the cylinder group index and the rotor\npositions straight from the on-disk group and caches them without any\ncheck:\n\n\tucpi->c_cgx = fs32_to_cpu(sb, ucg->cg_cgx);\n\tucpi->c_rotor = fs32_to_cpu(sb, ucg->cg_rotor);\n\tucpi->c_frotor = fs32_to_cpu(sb, ucg->cg_frotor);\n\tucpi->c_irotor = fs32_to_cpu(sb, ucg->cg_irotor);\n\nThey are then used as indices during allocation and free:\n\n - c_cgx indexes the cylinder summary array as\n UFS_SB(sb)->fs_cs(ucpi->c_cgx), so a value past s_ncg writes a 32\n bit count outside the s_csp allocation.\n\n - c_frotor becomes a bitmap scan start, start = c_frotor >> 3, and\n then length = ((s_fpg + 7) >> 3) - start. A start beyond the block\n bitmap wraps the unsigned length to a huge value, so ubh_scanc()\n walks far past the cylinder group buffers. c_irotor drives the\n inode bitmap the same way.\n\nA crafted image can set any of these freely, turning an ordinary\nallocation into an out of bounds access.\n\nReject a cylinder group whose recorded index does not match the group\nbeing read, or whose rotors fall outside the group, before the metadata\nis cached. Valid filesystems keep cg_cgx equal to the group number and\nthe rotors within the group, so only malformed images are rejected."
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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:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
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"baseScore": 7,
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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:L - The bad cg_cgx/cg_rotor/cg_frotor/cg_irotor values come from a crafted UFS image's cylinder group block, read by ufs_read_cylinder(). They are then used by the local VFS allocate/free paths (ufs_new_fragments, ufs_free_fragments, ufs_new_inode, ufs_free_inode). No network protocol carries these bytes.\nAC:H - ufs_load_cylinder() is called only from the allocate/free paths in balloc.c and ialloc.c. These need a read-write mount, and ufs_fill_super() returns -EROFS for one unless the non-default CONFIG_UFS_FS_WRITE (\"DANGEROUS\") is set. Major distros leave it off and only a few MIPS defconfigs set it, so reaching the bug depends on a rare kernel config.\nPR:N - The attacker only has to craft the image. The ufs file_system_type sets FS_REQUIRES_DEV without FS_USERNS_MOUNT, so the mount is done by a privileged victim, not the attacker. After that, creating or extending a file triggers the allocation.\nUI:R - A victim has to mount the attacker-supplied UFS image read-write before ufs_read_cylinder() caches the malformed cylinder group fields.\nS:U - The out-of-bounds accesses stay in kernel heap memory in the same kernel security authority. No guest/host or hardware boundary is crossed.\nC:H - If c_frotor/c_irotor lie outside the group, the unsigned length in ufs_bitmap_search() wraps. ubh_scanc() then reads far past the cylinder group buffers, an unbounded out-of-bounds read of kernel memory.\nI:H - ufs_add_fragments()/ufs_free_* call fs32_add() on UFS_SB(sb)->fs_cs(ucpi->c_cgx). An attacker-chosen c_cgx beyond s_ncg adds to a 32-bit value outside the s_csp heap allocation, an out-of-bounds heap write at a chosen index.\nA:H - The wild ubh_scanc() walk and the out-of-bounds fs_cs() writes can oops the kernel or corrupt the heap, crashing the system."
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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/ufs/cylinder.c"
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],
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"versions": [
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{
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"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "88cccb6beba136b73f0caf80e59457e1b3c0ca1e",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "f560a9e33365c460827c735fd86435f9213f1aed",
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"status": "affected",
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},
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{
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"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "e4c5cc9688c3e69d07d888853388549ae26c0521",
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"status": "affected",
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},
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{
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"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "58c0c414b2b8d099d33da494a354fa836ca6c10b",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "5902a95066883cf96fa15b2680694fc5dd0c7d11",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "87b12dc360a002eb2d498aa4f01e84347019612d",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "abde9eb33106850dfa367ad3965d3588bb8558d5",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "c9d263be26806d388129fab8c6904bed197fc6af",
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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/ufs/cylinder.c"
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],
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"versions": [
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{
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"version": "2.6.12",
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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": "2.6.12",
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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": "5.10.271",
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"lessThanOrEqual": "5.10.*",
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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": "5.15.222",
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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": "6.1.189",
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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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{
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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": "2.6.12",
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/88cccb6beba136b73f0caf80e59457e1b3c0ca1e"
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},
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{
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"url": "https://git.kernel.org/stable/c/f560a9e33365c460827c735fd86435f9213f1aed"
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},
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{
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"url": "https://git.kernel.org/stable/c/e4c5cc9688c3e69d07d888853388549ae26c0521"
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},
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{
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"url": "https://git.kernel.org/stable/c/58c0c414b2b8d099d33da494a354fa836ca6c10b"
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},
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{
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"url": "https://git.kernel.org/stable/c/5902a95066883cf96fa15b2680694fc5dd0c7d11"
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},
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{
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"url": "https://git.kernel.org/stable/c/87b12dc360a002eb2d498aa4f01e84347019612d"
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},
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{
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"url": "https://git.kernel.org/stable/c/abde9eb33106850dfa367ad3965d3588bb8558d5"
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},
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{
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"url": "https://git.kernel.org/stable/c/c9d263be26806d388129fab8c6904bed197fc6af"
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}
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],
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"title": "ufs: validate cylinder group metadata before caching it",
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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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} |