256 lines
14 KiB
JSON
256 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-2026-74356",
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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": "2026-08-15T05:44:03.887Z",
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"datePublished": "2026-08-15T05:58:41.445Z",
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"dateUpdated": "2026-10-30T12:29:51.074Z"
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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": "2026-10-30T12:29:51.074Z"
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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\nvhost: fix vhost_get_avail_idx for a non empty ring\n\nvhost_get_avail_idx is supposed to report whether it has updated\nvq->avail_idx. Instead, it returns whether all entries have been\nconsumed, which is usually the same. But not always - in\ndrivers/vhost/net.c and when mergeable buffers have been enabled, the\ndriver checks whether the combined entries are big enough to store an\nincoming packet. If not, the driver re-enables notifications with\navailable entries still in the ring. The incorrect return value from\nvhost_get_avail_idx propagates through vhost_enable_notify and causes\nthe host to livelock if the guest is not making progress, as vhost will\nimmediately disable notifications and retry using the available entries.\n\nThis goes back to commit d3bb267bbdcb (\"vhost: cache avail index in\nvhost_enable_notify()\") which changed vhost_enable_notify() to compare\nthe freshly read avail index against vq->last_avail_idx instead of the\npreviously cached vq->avail_idx. Commit 7ad472397667 (\"vhost: move\nsmp_rmb() into vhost_get_avail_idx()\") then carried over the same\ncomparison when refactoring vhost_enable_notify() to call the unified\nvhost_get_avail_idx().\n\nThe obvious fix is to make vhost_get_avail_idx do what the comment\nsays it does and report whether new entries have been added."
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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:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
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"baseScore": 7.4,
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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:A - Exploitation requires a malicious VM guest driving the virtio/vhost-net RX virtqueue on a KVM host; inbound packets cross the adjacent virtual-network boundary into host vhost-net processing, matching kernel CNA precedent for guest-to-host vhost-net bugs.\nAC:L - A guest can deterministically enable mergeable RX buffers, post undersized descriptors, stop refilling, and sustain inbound traffic so handle_rx() repeatedly hits the faulty vhost_enable_notify()/vhost_get_avail_idx() loop without races or rare configs.\nPR:N - A cloud VM tenant or any attacker with code execution inside a vhost-net guest needs no host root, capabilities, or /dev/vhost-net access—only control of the guest virtio RX ring and normal VM networking, which QEMU/KVM provides by default.\nUI:N - No host administrator or victim user action is required beyond standard VM operation; the guest attacker directly manipulates virtio descriptors and can generate or receive the RX traffic that triggers host-side vhost processing.\nS:C - The livelock executes in host kernel vhost worker context while processing guest-controlled virtio ring state, crossing the VM/host isolation boundary and degrading availability for the hypervisor and co-hosted workloads beyond the guest's own scope.\nC:N - This is a pure logic error in available-index comparison causing a notification retry loop; there is no memory corruption, out-of-bounds access, use-after-free, or other primitive that could disclose kernel memory.\nI:N - No kernel memory is corrupted or written beyond the virtio notification state machine; the bug cannot be leveraged for arbitrary write, control-flow hijacking, or code execution on the host.\nA:H - The faulty vhost_enable_notify() loop causes host CPU livelock when the guest stops making progress, pinning a vhost worker at 100% and denying service to the host and other VMs until the offending guest is stopped or killed."
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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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"drivers/vhost/vhost.c"
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],
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"versions": [
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{
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"version": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "7536f8f72bd24f1ae316c24231faaa3667eba837",
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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": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "0fe5ca2d56f0122988016e415a074c95925504b7",
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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": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "e115471008111f894c6528d9ab2ce7d0ce306f35",
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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": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "7f229d27bf27c7e589eca690d8612763a7a4801f",
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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": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "a9326b652bc7acd748d7a1143573845c7924d847",
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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": "d3bb267bbdcba199568f1325743d9d501dea0560",
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"lessThan": "09861858a68342f851f71c669ac0f69865c32151",
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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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"drivers/vhost/vhost.c"
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],
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"versions": [
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{
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"version": "5.18",
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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": "5.18",
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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": "6.1.191",
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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": "6.6.160",
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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": "6.12.97",
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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": "6.18.40",
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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": "7.1.5",
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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": "5.18",
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"versionEndExcluding": "6.1.191"
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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": "5.18",
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"versionEndExcluding": "6.6.160"
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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": "5.18",
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"versionEndExcluding": "6.12.97"
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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": "5.18",
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"versionEndExcluding": "6.18.40"
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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": "5.18",
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"versionEndExcluding": "7.1.5"
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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": "5.18",
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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/7536f8f72bd24f1ae316c24231faaa3667eba837"
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},
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{
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"url": "https://git.kernel.org/stable/c/0fe5ca2d56f0122988016e415a074c95925504b7"
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},
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{
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"url": "https://git.kernel.org/stable/c/e115471008111f894c6528d9ab2ce7d0ce306f35"
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},
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{
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"url": "https://git.kernel.org/stable/c/7f229d27bf27c7e589eca690d8612763a7a4801f"
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},
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{
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"url": "https://git.kernel.org/stable/c/a9326b652bc7acd748d7a1143573845c7924d847"
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},
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{
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"url": "https://git.kernel.org/stable/c/09861858a68342f851f71c669ac0f69865c32151"
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}
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],
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"title": "vhost: fix vhost_get_avail_idx for a non empty ring",
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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-2026-74356",
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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": "partial"
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}
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],
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"version": "2.0.3",
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"timestamp": "2026-10-16T18:54:24.183895Z"
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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": "2026-10-16T18:55:35.157Z"
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}
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}
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]
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}
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} |