228 lines
14 KiB
JSON
228 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-2025-21884",
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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": "2024-12-29T08:45:45.782Z",
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"datePublished": "2025-03-27T14:57:12.486Z",
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"dateUpdated": "2026-10-15T21:51:54.699Z"
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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": "2026-08-05T11:55:06.894Z"
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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\nnet: better track kernel sockets lifetime\n\nWhile kernel sockets are dismantled during pernet_operations->exit(),\ntheir freeing can be delayed by any tx packets still held in qdisc\nor device queues, due to skb_set_owner_w() prior calls.\n\nThis then trigger the following warning from ref_tracker_dir_exit() [1]\n\nTo fix this, make sure that kernel sockets own a reference on net->passive.\n\nAdd sk_net_refcnt_upgrade() helper, used whenever a kernel socket\nis converted to a refcounted one.\n\n[1]\n\n[ 136.263918][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at\n[ 136.263918][ T35] sk_alloc+0x2b3/0x370\n[ 136.263918][ T35] inet6_create+0x6ce/0x10f0\n[ 136.263918][ T35] __sock_create+0x4c0/0xa30\n[ 136.263918][ T35] inet_ctl_sock_create+0xc2/0x250\n[ 136.263918][ T35] igmp6_net_init+0x39/0x390\n[ 136.263918][ T35] ops_init+0x31e/0x590\n[ 136.263918][ T35] setup_net+0x287/0x9e0\n[ 136.263918][ T35] copy_net_ns+0x33f/0x570\n[ 136.263918][ T35] create_new_namespaces+0x425/0x7b0\n[ 136.263918][ T35] unshare_nsproxy_namespaces+0x124/0x180\n[ 136.263918][ T35] ksys_unshare+0x57d/0xa70\n[ 136.263918][ T35] __x64_sys_unshare+0x38/0x40\n[ 136.263918][ T35] do_syscall_64+0xf3/0x230\n[ 136.263918][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f\n[ 136.263918][ T35]\n[ 136.343488][ T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at\n[ 136.343488][ T35] sk_alloc+0x2b3/0x370\n[ 136.343488][ T35] inet6_create+0x6ce/0x10f0\n[ 136.343488][ T35] __sock_create+0x4c0/0xa30\n[ 136.343488][ T35] inet_ctl_sock_create+0xc2/0x250\n[ 136.343488][ T35] ndisc_net_init+0xa7/0x2b0\n[ 136.343488][ T35] ops_init+0x31e/0x590\n[ 136.343488][ T35] setup_net+0x287/0x9e0\n[ 136.343488][ T35] copy_net_ns+0x33f/0x570\n[ 136.343488][ T35] create_new_namespaces+0x425/0x7b0\n[ 136.343488][ T35] unshare_nsproxy_namespaces+0x124/0x180\n[ 136.343488][ T35] ksys_unshare+0x57d/0xa70\n[ 136.343488][ T35] __x64_sys_unshare+0x38/0x40\n[ 136.343488][ T35] do_syscall_64+0xf3/0x230\n[ 136.343488][ T35] entry_SYSCALL_64_after_hwframe+0x77/0x7f"
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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 bug is triggered entirely through local syscalls — `unshare(CLONE_NEWUSER|CLONE_NEWNET)` to create the netns, netlink/rtnetlink to add a device and a delaying qdisc, then namespace exit to run `cleanup_net()`; the syzbot traces show the path rooted at `__x64_sys_unshare`. No remote peer input is required or sufficient to reach it.\nAC:L - The attacker controls both halves of the window: they configure the device/qdisc that holds the kernel socket's TX skb (e.g. netem delay) and they choose exactly when to destroy the namespace, so the socket reliably outlives `net_passive_dec()`; the syzkaller reproducer hit it repeatably. Namespace churn also lets the attacker groom the freed `net_cachep` object before the deferred `__sk_destruct()` runs.\nPR:L - An unprivileged local account can create the network namespace and its per-netns kernel sockets via unprivileged user namespaces (`unshare -Urn`), which is enabled by default on mainstream distributions and Android. CAP_NET_ADMIN inside the new netns — granted automatically — is enough to add the device and qdisc needed to delay the kernel socket's skbs.\nUI:N - The attacking process performs every step itself: create the namespace, configure the delaying queue, trigger MLD/NDISC transmission, and exit. No victim action or cooperating process is needed.\nS:U - The freed `struct net`/`net->gen` slab objects and the sockets that dereference them all live in the kernel's own security authority. No hypervisor, IOMMU, or sandbox boundary is crossed, so this is standard in-kernel corruption.\nC:H - The kernel socket retains a completely unreferenced `struct net *`, so after `net_passive_dec()` frees `net->gen` and returns the `struct net` to `net_cachep`, subsequent `sock_net(sk)` dereferences read reallocated slab contents — the same class of defect that produced a KASAN slab-use-after-free read in the companion commit `65161fb544aa`. A use-after-free on a long-lived, attacker-groomable object yields an information-disclosure primitive.\nI:H - `__sk_destruct()` performs `__netns_tracker_free(sock_net(sk), &sk->ns_tracker, false)` on the dangling pointer, driving `ref_tracker_free()`'s list unlink and counter updates into the freed-and-reallocated `struct net`, which is a write into attacker-groomed memory. Reallocating the freed slot with a fresh namespace also lets the stale socket operate on the wrong `struct net`, corrupting per-netns state and enabling escalation to control-flow hijack.\nA:H - Use-after-free of `struct net` and its freed `net->gen` array produces oopses and panics even when not weaponized, and the pre-fix condition additionally trips `ref_tracker_dir_exit()`'s WARN with `CONFIG_NET_NS_REFCNT_TRACKER=y` (fatal under `panic_on_warn`). The sequence can be repeated in a loop by an unprivileged user until the box crashes."
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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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"include/net/sock.h",
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"net/core/sock.c",
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"net/mptcp/subflow.c",
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"net/netlink/af_netlink.c",
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"net/rds/tcp.c",
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"net/smc/af_smc.c",
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"net/sunrpc/svcsock.c",
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"net/sunrpc/xprtsock.c"
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],
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"versions": [
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{
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"version": "0cafd77dcd032d1687efaba5598cf07bce85997f",
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"lessThan": "2668e038800b946d269f96ec1b258c01930a242c",
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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": "0cafd77dcd032d1687efaba5598cf07bce85997f",
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"lessThan": "4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb",
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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": "0cafd77dcd032d1687efaba5598cf07bce85997f",
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"lessThan": "c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c",
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"status": "affected",
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},
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{
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"version": "0cafd77dcd032d1687efaba5598cf07bce85997f",
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"lessThan": "5c70eb5c593d64d93b178905da215a9fd288a4b5",
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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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"include/net/sock.h",
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"net/core/sock.c",
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"net/mptcp/subflow.c",
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"net/netlink/af_netlink.c",
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"net/rds/tcp.c",
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"net/smc/af_smc.c",
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"net/sunrpc/svcsock.c",
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"net/sunrpc/xprtsock.c"
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],
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"versions": [
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{
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"version": "6.2",
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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": "6.2",
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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": "6.6.103",
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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": "6.12.43",
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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": "6.13.6",
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"lessThanOrEqual": "6.13.*",
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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": "6.14",
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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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"nodes": [
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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": "6.2",
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"versionEndExcluding": "6.6.103"
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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/2668e038800b946d269f96ec1b258c01930a242c"
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},
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{
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"url": "https://git.kernel.org/stable/c/4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb"
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},
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{
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"url": "https://git.kernel.org/stable/c/c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c"
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},
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{
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"url": "https://git.kernel.org/stable/c/5c70eb5c593d64d93b178905da215a9fd288a4b5"
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}
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],
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"title": "net: better track kernel sockets lifetime",
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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-2025-21884",
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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": "2026-10-15T21:43:27.839000Z"
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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": "2026-10-15T21:51:54.699Z"
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}
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}
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]
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}
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} |