193 lines
12 KiB
JSON
193 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-2026-74640",
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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": "2026-08-15T05:44:03.922Z",
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"datePublished": "2026-08-22T15:32:18.957Z",
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"dateUpdated": "2026-10-16T19:06:04.418Z"
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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": "2026-08-25T05:41:01.874Z"
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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\nALSA: FCP: fix OOB write in fcp_meter_ctl_get()\n\nfcp_ioctl_set_meter_map() bounds the user-supplied Level Meter map size\nby the driver's own limit of 255\n\n\tif (map.map_size < 1 || map.map_size > 255 ||\n\t map.meter_slots < 1 || map.meter_slots > 255)\n\t\treturn -EINVAL;\n\nand passes it to fcp_add_new_ctl() as the control's channel count, where\nit is stored as elem->channels.\n\nEvery control read writes into struct snd_ctl_elem_value, whose integer\narray is declared long value[128], so the limit is 128, not 255.\nfcp_meter_ctl_get() stores one 64-bit word per channel into that array\nwith no bound of its own:\n\n\tfor (i = 0; i < elem->channels; i++) {\n\t\tint idx = private->meter_level_map[i];\n\t\tint value = idx < 0 ? 0 : le32_to_cpu(resp[idx]);\n\n\t\tucontrol->value.integer.value[i] = value;\n\t}\n\nsnd_ctl_elem_read_user() serves that object from\nmemdup_user(_control, sizeof(*control)), 1224 bytes on LP64 out of\nkmalloc-2048. offsetof(struct snd_ctl_elem_value, value) is 72, so\nelement i is written at byte 72 + 8 * i and element 144 already lands\npast the allocation. At map_size 255 the last store ends at byte 2112,\n888 bytes past the object and 64 bytes into the adjacent slab object.\nThe stored words come from the device and meter_level_map[] selects\nwhich word lands in which slot, so extent and contents are both\ncontrolled.\n\nThe core does not catch this. snd_ctl_check_elem_info() is reached only\nfrom __snd_ctl_elem_info(), which snd_ctl_elem_read() calls under\nCONFIG_SND_CTL_DEBUG; without that option snd_ctl_skip_validation() is a\ncompile-time true. __snd_ctl_add_replace() validates kcontrol->count and\nnever inspects elem->channels.\n\nInstalling an oversized map needs CAP_SYS_RAWIO, but the control outlives\nthe hwdep descriptor that created it, so the out-of-bounds stores are\nissued by any process able to read controls on /dev/snd/controlC0.\n\nKASAN on 7.2.0-rc5 (arm64), triggered by an unprivileged control read:\n\n BUG: KASAN: slab-out-of-bounds in fcp_meter_ctl_get\n Write of size 8 at addr ffff000017af04c8 by task fcp_trigger/185\n __asan_store8\n fcp_meter_ctl_get\n snd_ctl_elem_read\n snd_ctl_ioctl\n Allocated by task 185:\n memdup_user\n snd_ctl_ioctl\n The buggy address is located 0 bytes to the right of\n allocated 1224-byte region [ffff000017af0000, ffff000017af04c8)\n\nBound the map size by the ABI limit rather than by 255, and bound the\nstore loop at the sink so it cannot run past the value array whatever\nelem->channels holds.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>"
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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 - Exploitation is triggered by a local process issuing SNDRV_CTL_IOCTL_ELEM_READ on /dev/snd/controlC0, which reaches fcp_meter_ctl_get() via snd_ctl_elem_read_user(); there is no network, Bluetooth, or remote packet path to this code.\nAC:L - After a Level Meter map with map_size above 128 is configured, each control read deterministically performs up to 888 bytes of out-of-bounds 64-bit stores past the kmalloc-2048 buffer; no races or attacker-uncontrollable timing are required.\nPR:L - KASAN reproduced the slab OOB write from an unprivileged control read; snd_ctl_open has no capability check and the Level Meter control persists after hwdep close, so any local user with /dev/snd/controlC0 access can trigger it after normal fcp-server setup.\nUI:N - The attacker directly opens /dev/snd/controlC0 and issues the elem-read ioctl themselves; no separate victim action such as opening a file or mounting a filesystem is required.\nS:U - Impact is kernel heap corruption and local privilege escalation within the host kernel; it does not cross VM, container, or IOMMU security boundaries.\nC:H - Out-of-bounds writes corrupt up to 888 bytes beyond snd_ctl_elem_value into adjacent slab objects; attacker-influenced meter_level_map selects written values, enabling heap grooming and potential arbitrary kernel memory disclosure.\nI:H - Unbounded 64-bit stores past the 128-element value array corrupt adjacent kmalloc-2048 slab data with partially attacker-controlled contents, providing a heap corruption primitive suitable for kernel code or data overwrite.\nA:H - KASAN reported slab-out-of-bounds writes during an unprivileged control read; corrupting adjacent slab objects can cause kernel oops, panic, or hang, confirming 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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"sound/usb/fcp.c"
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],
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"versions": [
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{
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"version": "46757a3e7d50dac923888e7fbe68377736f13c70",
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"lessThan": "bb30e35c36ed00f24fa39aded811f64230a913b0",
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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": "46757a3e7d50dac923888e7fbe68377736f13c70",
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"lessThan": "bb61dc2ae59026f76db26e1909746908bc5b6f31",
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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": "46757a3e7d50dac923888e7fbe68377736f13c70",
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"lessThan": "620f1e52a46f604635efd0fb78138afd6a513b5d",
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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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"sound/usb/fcp.c"
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],
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"versions": [
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{
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"version": "6.14",
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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": "6.14",
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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": "6.18.45",
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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": "7.1.9",
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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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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.14",
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"versionEndExcluding": "6.18.45"
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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": "6.14",
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"versionEndExcluding": "7.1.9"
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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": "6.14",
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"versionEndExcluding": "7.2"
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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/bb30e35c36ed00f24fa39aded811f64230a913b0"
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},
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{
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"url": "https://git.kernel.org/stable/c/bb61dc2ae59026f76db26e1909746908bc5b6f31"
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},
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{
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"url": "https://git.kernel.org/stable/c/620f1e52a46f604635efd0fb78138afd6a513b5d"
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}
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],
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"title": "ALSA: FCP: fix OOB write in fcp_meter_ctl_get()",
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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-2026-74640",
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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": "2026-10-16T19:03:29.066751Z"
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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": "2026-10-16T19:06:04.418Z"
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}
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}
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]
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}
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} |