226 lines
14 KiB
JSON
226 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-2026-53360",
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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": "2026-06-09T07:44:35.400Z",
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"datePublished": "2026-07-04T11:53:58.657Z",
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"dateUpdated": "2026-10-19T20:07:44.426Z"
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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": "2026-08-05T12:35:09.892Z"
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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\nKVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use\n\nAs per the GHCB spec, when using GHCB v2+ require the software scratch area\nto reside in the GHCB's shared buffer. Note, things like Page State Change\n(PSC) requests _rely_ on this behavior, as the guest can't provide a length\nwhen making the request, i.e. the size of the guest payload is bounded by\nthe size of the shared buffer.\n\nFailure to force usage of the GHCB, and a slew of other flaws, lets a\nmalicious SNP guest corrupt host kernel heap memory, and leak host heap\nlayout information.\n\nsetup_vmgexit_scratch() allocates a buffer via kvzalloc(exit_info_2),\nwhere exit_info_2 is guest-controlled. With exit_info_2=24, this yields\na 24-byte allocation in kmalloc-cg-32 (32-byte slab objects). The buffer\nholds an 8-byte psc_hdr followed by 8-byte psc_entry structs, so only\nentries[0] and entries[1] are in-bounds.\n\nsnp_begin_psc() validates end_entry against VMGEXIT_PSC_MAX_COUNT (253)\nbut NOT against the actual buffer size:\n\n idx_end = hdr->end_entry;\n\n if (idx_end >= VMGEXIT_PSC_MAX_COUNT) { // checks 253, not buffer\n snp_complete_psc(svm, ...);\n return 1;\n }\n\n for (idx = idx_start; idx <= idx_end; idx++) {\n entry_start = entries[idx]; // OOB when idx >= 2\n\nThe guest sets end_entry=10+, causing the host to iterate entries[2+]\nwhich are OOB into adjacent slab objects. For each OOB entry:\n\n - The host reads 8 bytes (OOB READ / info leak oracle)\n - If the data passes PSC validation, __snp_complete_one_psc() writes\n cur_page = 1 or 512 into the entry (OOB WRITE, sev.c:3806)\n - If validation fails, the error response reveals whether adjacent\n memory is zero vs non-zero (information disclosure to guest)\n\nThe guest controls allocation size (exit_info_2), entry range\n(cur_entry/end_entry), and can fire unlimited VMGEXITs to repeatedly\nhit different slab positions.\n\nBy exploiting the variety of bugs, a malicious SEV-SNP guest can:\n - OOB read adjacent kmalloc-cg-32 objects (heap layout disclosure)\n - OOB write cur_page bits into adjacent objects (heap corruption)\n - Trigger use-after-free conditions across VMGEXITs\n\nE.g. with KASAN enabled, a single insmod of the PoC guest module\nproduces 73 KASAN reports:\n\n BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x126/0x890\n Read of size 8 at addr ffff888219ffb5e0 by task qemu-system-x86/2199\n\n BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x468/0x890\n Write of size 8 at addr ffff888351566648 by task qemu-system-x86/2199\n\n The buggy address belongs to the object at ffff888XXXXXXXXX\n which belongs to the cache kmalloc-cg-32 of size 32\n The buggy address is located N bytes to the right of\n allocated 32-byte region [ffff888XXXXXXXXX, ffff888XXXXXXXXX)\n\n Breakdown:\n 62 slab-out-of-bounds (reads + writes past allocation)\n 7 slab-use-after-free\n 4 use-after-free\n\nAll credit to Stan for the wonderful description and reproducer!\n\n[sean: write changelog]"
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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:L/UI:N/S:C/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:L - The vulnerable path is reached by running a SEV-SNP vCPU through KVM and issuing a guest-controlled VMGEXIT PSC request, not by remote packets or adjacent/physical access.\nAC:L - The guest directly controls the scratch pointer/length and PSC entry bounds, and can repeatedly issue malformed VMGEXITs without needing external races or rare timing conditions.\nPR:L - Exploitation requires the ability to run or control a SEV-SNP guest/KVM vCPU, which is a low-privilege local or tenant capability rather than real host root in the init namespace.\nUI:N - Once the attacker controls the malicious guest or VM process, no additional victim action is required to trigger the VMGEXIT handling path.\nS:C - The bug lets a malicious guest corrupt and disclose host kernel heap memory, crossing the guest-to-host virtualization security boundary.\nC:H - The OOB reads and error oracle leak adjacent host heap contents/layout, and the associated memory corruption/UAF behavior is sufficient to treat confidentiality impact as high.\nI:H - The vulnerable path performs OOB writes into adjacent host slab objects and can trigger UAF conditions, making host kernel memory corruption and potential control-flow compromise defensible.\nA:H - The bug produces host kernel slab OOB writes/reads and UAF reports and can crash or destabilize the host kernel, giving high availability impact."
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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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"arch/x86/kvm/svm/sev.c"
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],
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"versions": [
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{
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"version": "4af663c2f64a8d252e690c60cf8b8abf22dc2951",
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"lessThan": "bf9ba093fbb83c0c9a3dedd50efec29424eca2fc",
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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": "4af663c2f64a8d252e690c60cf8b8abf22dc2951",
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"lessThan": "c9b4198fbc6ed99a9da4bee9f74bb730f926c9ae",
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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": "4af663c2f64a8d252e690c60cf8b8abf22dc2951",
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"lessThan": "b328ede59ac34e7998e1eee5e5f0cc26c2a91846",
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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": "4af663c2f64a8d252e690c60cf8b8abf22dc2951",
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"lessThan": "db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7",
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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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"arch/x86/kvm/svm/sev.c"
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],
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"versions": [
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{
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"version": "6.10",
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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": "6.10",
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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": "6.12.93",
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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": "6.18.35",
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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": "7.0.12",
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"lessThanOrEqual": "7.0.*",
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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",
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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": "6.10",
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"versionEndExcluding": "6.12.93"
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},
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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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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.10",
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},
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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": "6.10",
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"versionEndExcluding": "7.1"
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}
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]
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}
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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/bf9ba093fbb83c0c9a3dedd50efec29424eca2fc"
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},
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{
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"url": "https://git.kernel.org/stable/c/c9b4198fbc6ed99a9da4bee9f74bb730f926c9ae"
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},
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{
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"url": "https://git.kernel.org/stable/c/b328ede59ac34e7998e1eee5e5f0cc26c2a91846"
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},
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{
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"url": "https://git.kernel.org/stable/c/db3f2195d29344a3cf1e9dd9ab7f21ced7308cf7"
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}
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],
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"title": "KVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use",
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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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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2026-53360",
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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": "2026-10-16T15:29:05.458760Z"
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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-787",
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"description": "CWE-787 Out-of-bounds Write"
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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": "2026-10-19T20:07:44.426Z"
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}
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}
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]
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}
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} |