252 lines
12 KiB
JSON
252 lines
12 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-2021-46977",
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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": "2024-02-27T18:42:55.944Z",
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"datePublished": "2024-02-28T08:13:08.489Z",
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"dateUpdated": "2026-08-05T08:45:21.421Z"
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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": "2026-08-05T08:45:21.421Z"
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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: VMX: Disable preemption when probing user return MSRs\n\nDisable preemption when probing a user return MSR via RDSMR/WRMSR. If\nthe MSR holds a different value per logical CPU, the WRMSR could corrupt\nthe host's value if KVM is preempted between the RDMSR and WRMSR, and\nthen rescheduled on a different CPU.\n\nOpportunistically land the helper in common x86, SVM will use the helper\nin a future commit."
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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: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 vulnerable probe runs during KVM_CREATE_VCPU in vmx_create_vcpu, reachable only via local /dev/kvm ioctls (KVM_CREATE_VM then KVM_CREATE_VCPU), not from network packets or guest-only operations.\nAC:L - An attacker with KVM access can repeatedly create vCPUs while running concurrent vCPU threads and forcing migrations via affinity/load, so they can drive both the probe and the conditions that leave differing MSR values on CPUs; success does not depend on a victim-controlled state.\nPR:L - The kernel imposes no capability check on /dev/kvm; access is only file permission based, and common deployments (kvm group, nested virt, crosvm) grant this to unprivileged users, so root/admin is not required.\nUI:N - Exploitation requires only attacker-issued KVM ioctls; no separate victim action such as mounting a filesystem or opening a crafted file is needed.\nS:U - The attacker is already host userspace with KVM access; impact remains under the host kernel authority rather than a guest-to-host escape across a VM boundary.\nC:H - User-return MSRs (including LSTAR/TSC_AUX) can still hold guest values while kernel code runs, and the probe's raw WRMSR bypasses user-return tracking, so attacker-controlled guest MSR contents can be planted on another host CPU and enable SYSCALL-path hijacking and arbitrary host memory disclosure.\nI:H - Planting attacker-influenced syscall MSRs (especially LSTAR) onto a host CPU redirects subsequent host SYSCALL entry, which is exploitable for control-flow hijacking and arbitrary host integrity compromise beyond a simple per-CPU TSC_AUX mixup.\nA:H - Corrupting host user-return MSRs (wrong LSTAR/STAR/TSC_AUX) reliably breaks host syscall handling or CPU identity and can cause kernel oopses, panics, or hard system failure on the affected CPU."
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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/include/asm/kvm_host.h",
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"arch/x86/kvm/vmx/vmx.c",
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"arch/x86/kvm/x86.c"
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],
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"versions": [
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{
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"version": "4be5341026246870818e28b53202b001426a5aec",
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"lessThan": "31f29749ee970c251b3a7e5b914108425940d089",
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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": "4be5341026246870818e28b53202b001426a5aec",
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"lessThan": "5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94",
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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": "4be5341026246870818e28b53202b001426a5aec",
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"lessThan": "e3ea1895df719c4ef87862501bb10d95f4177bed",
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"status": "affected",
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"lessThan": "5104d7ffcf24749939bea7fdb5378d186473f890",
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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/include/asm/kvm_host.h",
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"arch/x86/kvm/vmx/vmx.c",
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"arch/x86/kvm/x86.c"
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],
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"versions": [
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{
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"version": "5.5",
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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": "5.5",
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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": "5.10.38",
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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": "5.11.22",
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"lessThanOrEqual": "5.11.*",
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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": "5.12.5",
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"lessThanOrEqual": "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": "5.13",
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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": "5.5",
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"versionEndExcluding": "5.10.38"
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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": "5.5",
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"versionEndExcluding": "5.11.22"
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.5",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.5",
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/31f29749ee970c251b3a7e5b914108425940d089"
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},
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{
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"url": "https://git.kernel.org/stable/c/5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94"
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},
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{
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"url": "https://git.kernel.org/stable/c/e3ea1895df719c4ef87862501bb10d95f4177bed"
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},
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{
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"url": "https://git.kernel.org/stable/c/5104d7ffcf24749939bea7fdb5378d186473f890"
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}
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],
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"title": "KVM: VMX: Disable preemption when probing user return MSRs",
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"adp": [
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"content": {
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"timestamp": "2024-06-21T16:27:41.559362Z",
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"id": "CVE-2021-46977",
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"options": [
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{
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"Exploitation": "none"
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2024-08-04T05:24:38.401Z"
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