264 lines
16 KiB
JSON
264 lines
16 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-2026-68370",
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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": "2026-07-30T09:28:09.386Z",
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"datePublished": "2026-08-10T12:03:48.320Z",
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"dateUpdated": "2026-08-19T16:34:31.156Z"
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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": "2026-08-19T16:34:31.156Z"
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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\nusb: gadget: dummy_hcd: prevent fifo_req reuse during giveback\n\ndummy_hcd embeds a single shared usb_request (dum->fifo_req) that the\n\"emulated single-request FIFO\" fast-path in dummy_queue() reuses for\nsmall IN transfers: it copies the caller's request into it\n(req->req = *_req) and queues it, treating list_empty(&fifo_req.queue)\nas \"the slot is free\".\n\nThe completion side (dummy_timer/transfer/nuke/dummy_dequeue) follows\nthe standard pattern: list_del_init(&req->queue) unlinks the request,\nthen the lock is dropped and usb_gadget_giveback_request() invokes\nreq->complete(). But list_del_init() makes fifo_req.queue look empty\n*before* the completion callback returns, so a concurrent dummy_queue()\non another CPU sees the slot as free, reuses fifo_req and runs\nreq->req = *_req -- overwriting req->complete while dummy_timer is\nmid-calling it. The indirect call then jumps to a clobbered pointer,\ncausing a general protection fault / page fault in dummy_timer\n(syzkaller extid faf3a6cf579fc65591ca). The clobbering write is an\nin-bounds memcpy on a live shared object, so KASAN cannot flag it.\n\nAdd a fifo_req_busy bit covering the shared request's whole lifetime:\nset it in dummy_queue() when the FIFO fast-path takes fifo_req (making\nit the fast-path guard, replacing the list_empty(&fifo_req.queue)\ntest), and clear it after the completion callback has returned, via a\ndummy_giveback() helper used at all four gadget-request giveback\nsites. The shared slot can no longer be reused until its completion\ncallback has finished."
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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 - dummy_hcd is a purely virtual UDC/HCD pair with no physical port; both sides of the race are driven locally — gadget-side `usb_ep_queue()` via raw-gadget ioctls, gadgetfs/functionfs endpoint writes or configfs function traffic, and the host side by the in-software `dummy_timer`/URB path. No cable, hardware, or network access is involved, matching the AV:L used for other dummy_hcd/gadget bugs.\nAC:L - The attacker controls both sides of the race: it queues small IN requests on one CPU in a tight loop while the periodic 1 ms `dummy_timer` frame processing performs giveback on another, and the fast-path guard (`list_empty(&fifo_req.queue)`) is cleared before the callback returns, so the window is entered on essentially every iteration and can be retried indefinitely.\nPR:L - No capability check exists anywhere on the path — `dummy_queue()` and the giveback sites perform none; reachability is gated only by node/mount permissions on /dev/raw-gadget, gadgetfs or the gadget configfs/functionfs tree, which on Android and embedded/industrial systems are routinely delegated to non-root system accounts, so basic local access suffices.\nUI:N - The attacker performs every step itself — enabling the gadget, queueing the IN transfers, and letting the emulated frame timer run — with no action required from any other user or victim.\nS:U - The corrupted object and the resulting control-flow hijack are entirely within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The in-flight copy overwrites `fifo_req.req.buf`, `length`, `actual` and `context` of the live shared request, so the completion path and the host-side `transfer()` memcpy operate with mismatched buffer/length/context pairs, letting an attacker steer reads out of unintended kernel memory and surface them through the emulated host transfer — a kernel memory disclosure primitive.\nI:H - `req->req = *_req` clobbers the `complete` function pointer while `usb_gadget_giveback_request()` is dereferencing it, giving a torn/stale indirect call plus a `context` mismatch (type confusion) that is a direct control-flow hijack primitive; the same race also lets the shared `fifo_buf` be written under a stale length, yielding controllable kernel writes.\nA:H - The reported effect is a general protection fault / kernel page fault in `dummy_timer` (syzbot faf3a6cf579fc65591ca) from calling through the clobbered pointer, i.e. a kernel oops that an unprivileged local attacker can trigger repeatedly."
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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/usb/gadget/udc/dummy_hcd.c"
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],
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"versions": [
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{
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"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "16a685172abc9233728830e27d26ffa778975b51",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "95f30a21612cc65761c58ba044b1767699437317",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "3cab0e5498d0fbb21fe1a9181f7bda9a844a697e",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "e2b2740f1242bc70b5b46da2cdbbaa419f490e59",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "67b589d09a96882d56842dced5698ed8dd06ce45",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "e239ea91b48180ed48a86ac25643832a02c88456",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "e24b33618231034bf01dfaff4fd3409d4b4d5b2e",
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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": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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"lessThan": "d5e5cd3654d2b5359a12ea6586120f05b28634ee",
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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/usb/gadget/udc/dummy_hcd.c"
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],
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"versions": [
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{
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"version": "2.6.12",
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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": "2.6.12",
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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": "5.10.265",
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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": "5.15.216",
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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": "6.1.183",
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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": "6.6.148",
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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": "6.12.101",
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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": "6.18.42",
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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": "7.1.6",
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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": "2.6.12",
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"versionEndExcluding": "5.10.265"
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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": "2.6.12",
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"versionEndExcluding": "5.15.216"
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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": "2.6.12",
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"versionEndExcluding": "6.1.183"
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "2.6.12",
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"versionEndExcluding": "6.6.148"
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "2.6.12",
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"versionEndExcluding": "6.12.101"
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "2.6.12",
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"versionEndExcluding": "7.1.6"
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},
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{
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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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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/16a685172abc9233728830e27d26ffa778975b51"
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},
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{
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"url": "https://git.kernel.org/stable/c/95f30a21612cc65761c58ba044b1767699437317"
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},
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{
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"url": "https://git.kernel.org/stable/c/3cab0e5498d0fbb21fe1a9181f7bda9a844a697e"
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},
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{
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"url": "https://git.kernel.org/stable/c/e2b2740f1242bc70b5b46da2cdbbaa419f490e59"
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},
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{
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"url": "https://git.kernel.org/stable/c/67b589d09a96882d56842dced5698ed8dd06ce45"
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},
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{
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"url": "https://git.kernel.org/stable/c/e239ea91b48180ed48a86ac25643832a02c88456"
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},
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{
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"url": "https://git.kernel.org/stable/c/e24b33618231034bf01dfaff4fd3409d4b4d5b2e"
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},
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{
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"url": "https://git.kernel.org/stable/c/d5e5cd3654d2b5359a12ea6586120f05b28634ee"
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}
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],
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"title": "usb: gadget: dummy_hcd: prevent fifo_req reuse during giveback",
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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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}
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} |