180 lines
10 KiB
JSON
180 lines
10 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-2026-93121",
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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": "2026-09-17T16:02:15.086Z",
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"datePublished": "2026-09-17T16:11:27.220Z",
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"dateUpdated": "2026-10-19T09:05:54.766Z"
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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": "2026-10-19T09:05:54.766Z"
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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: f_fs: Fix fence cleanup in ffs_dmabuf_transfer() error paths\n\nThe error paths for endpoint-disabled (ESHUTDOWN) and request-allocation\nfailure (ENOMEM) in ffs_dmabuf_transfer() jump to err_fence_put which\ncalls dma_fence_put() on the fence. However, at that point the fence has\nonly been kmalloc'd — dma_fence_init() has not been called yet, so the\nrefcount and the fence ops are uninitialized. Calling dma_fence_put() on\nsuch an object leads to undefined behavior.\n\nUse kfree() instead, since the fence is just a plain allocation at this\nstage, and rename the label to err_fence_free to reflect the actual\ncleanup action."
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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:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7,
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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 uninitialized fence is kmalloc'd and then dma_fence_put() in ffs_dmabuf_transfer(), reached only from ffs_epfile_ioctl()'s FUNCTIONFS_DMABUF_TRANSFER case after copy_from_user of usb_ffs_dmabuf_transfer_req; USB host traffic never supplies that ioctl or the fence object.\nAC:H - err_fence_put runs only when epfile->ep != ep after ffs_epfile_wait_ep() (epfile->ep is NULLed solely by ffs_func_eps_disable() from gadget set_alt/disable/unbind) or when usb_ep_alloc_request(..., GFP_ATOMIC) fails; the ioctl caller cannot invoke those gadget callbacks and cannot reliably force that small GFP_ATOMIC allocation to fail.\nPR:L - ffs_epfile_ioctl() has no capable() check; FUNCTIONFS_DMABUF_TRANSFER only needs the endpoint file open. FunctionFS inodes take uid/gid/mode from ffs_fs_parse_param() (uid=/gid=/fmode=), which deployed gadgets use to hand ep nodes to non-root daemons such as adbd.\nUI:N - The attacker issues FUNCTIONFS_DMABUF_TRANSFER themselves on an endpoint fd they already hold; ffs_epfile_wait_ep() needing a prior host SET_CONFIGURATION is ambient gadget enumeration, not a victim action at exploit time.\nS:U - dma_fence_put() on the kmalloc'd ffs_dma_fence runs dma_fence_release() in the same kernel that hosts FunctionFS, so impact stays inside that kernel's privilege boundary rather than crossing a VM or IOMMU authority.\nC:H - kmalloc_obj(*fence) is not zeroed and dma_fence_init() has not run, so fence->refcount and fence->ops are leftover heap contents; dma_fence_put() calls dma_fence_release() if the sprayed refcount is 1, which rcu_dereference()s ops and reads other fence fields.\nI:H - dma_fence_release() calls ops->release() through the uninitialized fence->ops pointer (or walks garbage cb_list in the pending-signal path); a same-cache heap spray can point ops at attacker-controlled function pointers for control-flow hijack.\nA:H - dma_fence_release() does list_empty(&fence->cb_list) and dma_fence_lock_irqsave() on uninitialized cb_list/lock and may invoke a wild ops->release(), any of which oopses or panics when the ESHUTDOWN or ENOMEM err_fence_put path runs."
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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/function/f_fs.c"
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],
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"versions": [
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{
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"version": "7b07a2a7ca02a20124b552be96c5a56910795488",
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"lessThan": "be539138d9a187af3b884525a395db10797c64f1",
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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": "7b07a2a7ca02a20124b552be96c5a56910795488",
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"lessThan": "5fd8baacc7dc477df9cac61b45491840247a9b1e",
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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": "7b07a2a7ca02a20124b552be96c5a56910795488",
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"lessThan": "58952c83dfe6ea3294a74734d2d1018c1120779a",
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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": "7b07a2a7ca02a20124b552be96c5a56910795488",
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"lessThan": "621707dc67c9846fd876d7579ec951d92aa033f1",
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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/function/f_fs.c"
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],
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"versions": [
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{
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"version": "6.9",
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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": "6.9",
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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": "6.12.110",
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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": "6.18.52",
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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": "7.2.6",
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"lessThanOrEqual": "7.2.*",
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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": "7.3",
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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": "6.9",
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"versionEndExcluding": "6.12.110"
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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": "6.9",
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"versionEndExcluding": "6.18.52"
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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": "6.9",
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"versionEndExcluding": "7.2.6"
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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": "6.9",
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"versionEndExcluding": "7.3"
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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/be539138d9a187af3b884525a395db10797c64f1"
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},
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{
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"url": "https://git.kernel.org/stable/c/5fd8baacc7dc477df9cac61b45491840247a9b1e"
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},
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{
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"url": "https://git.kernel.org/stable/c/58952c83dfe6ea3294a74734d2d1018c1120779a"
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},
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{
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"url": "https://git.kernel.org/stable/c/621707dc67c9846fd876d7579ec951d92aa033f1"
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}
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],
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"title": "usb: gadget: f_fs: Fix fence cleanup in ffs_dmabuf_transfer() error paths",
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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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} |