347 lines
20 KiB
JSON
347 lines
20 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-2021-47656",
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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": "2025-02-26T01:48:21.521Z",
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"datePublished": "2025-02-26T01:54:20.069Z",
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"dateUpdated": "2026-08-05T08:48:47.063Z"
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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": "2026-08-05T08:48:47.063Z"
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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\njffs2: fix use-after-free in jffs2_clear_xattr_subsystem\n\nWhen we mount a jffs2 image, assume that the first few blocks of\nthe image are normal and contain at least one xattr-related inode,\nbut the next block is abnormal. As a result, an error is returned\nin jffs2_scan_eraseblock(). jffs2_clear_xattr_subsystem() is then\ncalled in jffs2_build_filesystem() and then again in\njffs2_do_fill_super().\n\nFinally we can observe the following report:\n ==================================================================\n BUG: KASAN: use-after-free in jffs2_clear_xattr_subsystem+0x95/0x6ac\n Read of size 8 at addr ffff8881243384e0 by task mount/719\n\n Call Trace:\n dump_stack+0x115/0x16b\n jffs2_clear_xattr_subsystem+0x95/0x6ac\n jffs2_do_fill_super+0x84f/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n mtd_get_sb+0x254/0x400\n mtd_get_sb_by_nr+0x4f/0xd0\n get_tree_mtd+0x498/0x840\n jffs2_get_tree+0x25/0x30\n vfs_get_tree+0x8d/0x2e0\n path_mount+0x50f/0x1e50\n do_mount+0x107/0x130\n __se_sys_mount+0x1c5/0x2f0\n __x64_sys_mount+0xc7/0x160\n do_syscall_64+0x45/0x70\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\n Allocated by task 719:\n kasan_save_stack+0x23/0x60\n __kasan_kmalloc.constprop.0+0x10b/0x120\n kasan_slab_alloc+0x12/0x20\n kmem_cache_alloc+0x1c0/0x870\n jffs2_alloc_xattr_ref+0x2f/0xa0\n jffs2_scan_medium.cold+0x3713/0x4794\n jffs2_do_mount_fs.cold+0xa7/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n Freed by task 719:\n kmem_cache_free+0xcc/0x7b0\n jffs2_free_xattr_ref+0x78/0x98\n jffs2_clear_xattr_subsystem+0xa1/0x6ac\n jffs2_do_mount_fs.cold+0x5e6/0x2253\n jffs2_do_fill_super+0x383/0xc30\n jffs2_fill_super+0x2ea/0x4c0\n [...]\n\n The buggy address belongs to the object at ffff8881243384b8\n which belongs to the cache jffs2_xattr_ref of size 48\n The buggy address is located 40 bytes inside of\n 48-byte region [ffff8881243384b8, ffff8881243384e8)\n [...]\n ==================================================================\n\nThe triggering of the BUG is shown in the following stack:\n-----------------------------------------------------------\njffs2_fill_super\n jffs2_do_fill_super\n jffs2_do_mount_fs\n jffs2_build_filesystem\n jffs2_scan_medium\n jffs2_scan_eraseblock <--- ERROR\n jffs2_clear_xattr_subsystem <--- free\n jffs2_clear_xattr_subsystem <--- free again\n-----------------------------------------------------------\n\nAn error is returned in jffs2_do_mount_fs(). If the error is returned\nby jffs2_sum_init(), the jffs2_clear_xattr_subsystem() does not need to\nbe executed. If the error is returned by jffs2_build_filesystem(), the\njffs2_clear_xattr_subsystem() also does not need to be executed again.\nSo move jffs2_clear_xattr_subsystem() from 'out_inohash' to 'out_root'\nto fix this UAF problem."
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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:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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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:L - The bug is reached only through the local mount path (mount → jffs2_get_tree → get_tree_mtd → jffs2_fill_super → jffs2_do_fill_super → jffs2_do_mount_fs → jffs2_build_filesystem), parsing an MTD/JFFS2 image; there is no network-facing consumer.\nAC:L - An attacker who crafts the image fully controls the trigger—place valid XREF/XATTR nodes in early eraseblocks so jffs2_alloc_xattr_ref() populates xref_temp, then make a later block fail jffs2_scan_eraseblock()—with no race or attacker-uncontrollable condition.\nPR:N - The attacker needs no account on the target; they only supply the crafted JFFS2/MTD image (firmware blob, flash/SD contents), and CAP_SYS_ADMIN belongs to the victim or tooling that mounts it, matching the crafted-filesystem-image pattern.\nUI:R - Exploitation requires a victim (root, firmware updater, or automounter) to mount the attacker-supplied JFFS2 image so the failing scan hits the double clear_xattr path.\nS:U - The use-after-free corrupts kernel slab memory within the same host OS security authority; no VM escape, IOMMU bypass, or other cross-boundary compromise occurs.\nC:H - jffs2_clear_xattr_subsystem() frees xref_temp without NULLing it, so the second call reads ref->next from freed jffs2_xattr_ref slab objects; per guidance a UAF enables arbitrary kernel memory disclosure.\nI:H - The second pass double-frees attacker-populated jffs2_xattr_ref objects, enabling classic heap spraying and overlapping allocations for arbitrary write / control-flow hijack.\nA:H - The KASAN-confirmed use-after-free during mount produces a kernel oops/panic even without full exploitation, and is repeatable on every mount of the crafted image."
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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/jffs2/fs.c"
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],
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"versions": [
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{
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"version": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "9150cb625b46f68d524f4cfd491f1aafc23e10a9",
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"status": "affected",
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"lessThan": "3bd2454162ec6bbb5503233c804fce6e4b6dcec5",
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"status": "affected",
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},
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{
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"version": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "c3b07c875fa8f906f932976460fd14798596f101",
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"status": "affected",
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"status": "affected",
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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": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "7a75740206af5f17e9f3efa384211cba70213da1",
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"status": "affected",
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},
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{
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"version": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "22327bd7988f21de3a53c1373f3b81542bfe1f44",
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"status": "affected",
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},
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{
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"version": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "8c0f024f29e055840a5a89fe23b96ae3f921afed",
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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": "aa98d7cf59b5b0764d3502662053489585faf2fe",
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"lessThan": "4c7c44ee1650677fbe89d86edbad9497b7679b5c",
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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/jffs2/fs.c"
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],
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"versions": [
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{
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"version": "2.6.18",
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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": "2.6.18",
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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": "4.9.311",
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"lessThanOrEqual": "4.9.*",
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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": "4.14.276",
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"lessThanOrEqual": "4.14.*",
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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": "4.19.238",
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"lessThanOrEqual": "4.19.*",
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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": "5.4.189",
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"lessThanOrEqual": "5.4.*",
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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": "5.10.110",
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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": "5.15.33",
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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": "5.16.19",
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"lessThanOrEqual": "5.16.*",
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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": "5.17.2",
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"lessThanOrEqual": "5.17.*",
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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": "5.18",
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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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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "2.6.18",
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"versionEndExcluding": "4.9.311"
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/9150cb625b46f68d524f4cfd491f1aafc23e10a9"
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},
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{
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"url": "https://git.kernel.org/stable/c/3bd2454162ec6bbb5503233c804fce6e4b6dcec5"
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},
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{
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"url": "https://git.kernel.org/stable/c/c3b07c875fa8f906f932976460fd14798596f101"
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},
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{
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"url": "https://git.kernel.org/stable/c/30bf7244acf32f19cb722c39f7bc1c2a9f300422"
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},
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{
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"url": "https://git.kernel.org/stable/c/7bb7428dd73991bf4b3a7a61b493ca50046c2b13"
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},
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{
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"url": "https://git.kernel.org/stable/c/7a75740206af5f17e9f3efa384211cba70213da1"
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},
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{
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"url": "https://git.kernel.org/stable/c/22327bd7988f21de3a53c1373f3b81542bfe1f44"
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},
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{
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"url": "https://git.kernel.org/stable/c/8c0f024f29e055840a5a89fe23b96ae3f921afed"
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},
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{
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"url": "https://git.kernel.org/stable/c/4c7c44ee1650677fbe89d86edbad9497b7679b5c"
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}
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],
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"title": "jffs2: fix use-after-free in jffs2_clear_xattr_subsystem",
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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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"adp": [
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{
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"metrics": [
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{
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"cvssV3_1": {
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"scope": "UNCHANGED",
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"version": "3.1",
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"baseScore": 7.8,
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"attackVector": "LOCAL",
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"baseSeverity": "HIGH",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"integrityImpact": "HIGH",
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"userInteraction": "NONE",
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"attackComplexity": "LOW",
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"availabilityImpact": "HIGH",
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"privilegesRequired": "LOW",
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"confidentialityImpact": "HIGH"
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}
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},
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{
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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2021-47656",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "total"
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}
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],
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"version": "2.0.3",
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"timestamp": "2025-02-27T17:59:35.381270Z"
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}
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}
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}
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],
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"problemTypes": [
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{
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"descriptions": [
|
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{
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"lang": "en",
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"type": "CWE",
|
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"cweId": "CWE-416",
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"description": "CWE-416 Use After Free"
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}
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]
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2025-02-27T18:02:30.510Z"
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}
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}
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]
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}
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} |