256 lines
16 KiB
JSON
256 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-2026-74714",
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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": "2026-08-15T05:44:03.928Z",
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"datePublished": "2026-08-22T15:33:09.643Z",
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"dateUpdated": "2026-10-16T19:16:11.358Z"
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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": "2026-08-25T05:41:57.341Z"
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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\nbpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch()\n\nreqsk_queue_hash_req() publishes a TCP_NEW_SYN_RECV request_sock onto\nthe ehash chain, drops the bucket lock, and only afterwards sets\nrsk_refcnt to 3.\n\nLockless readers such as __inet_lookup_established() handle this with\nrefcount_inc_not_zero(), but bpf_iter_tcp_established_batch() uses plain\nsock_hold() while holding the bucket lock, on the assumption that the\nlock guarantees sk_refcnt > 0. That assumption does not hold for\nrequest_sock:\n\n CPU 0 CPU 1\n ----- -----\n tcp_conn_request()\n reqsk_queue_hash_req()\n inet_ehash_insert(req)\n spin_lock(bucket)\n __sk_nulls_add_node_rcu(req) // rsk_refcnt == 0\n spin_unlock(bucket)\n bpf_iter_tcp_established_batch()\n spin_lock(bucket)\n sock_hold(req) <-- addition on 0\n spin_unlock(bucket)\n refcount_set(&req->rsk_refcnt, 3) // clobbers saturated value\n\nwhich surfaces as:\n\n refcount_t: addition on 0; use-after-free.\n WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x48/0x90, CPU#1\n Call Trace:\n bpf_iter_tcp_established_batch+0x14e/0x170\n bpf_iter_tcp_batch+0x53/0x200\n bpf_iter_tcp_seq_next+0x27/0x70\n bpf_seq_read+0x107/0x410\n vfs_read+0xb9/0x380\n\nThe iterator's stolen reference is lost when the publishing CPU's\nrefcount_set() overwrites the count, leaving the socket one reference\nshort. When the last legitimate owner drops its reference the reqsk is\nfreed while still reachable, leading to use-after-free.\n\nThis reproduces in seconds with tcp_syncookies=0, a handful of threads\ndoing connect()/close() to a local listener while others read an\niter/tcp link in a tight loop.\n\nUse refcount_inc_not_zero() and skip the socket on failure. A skipped\nsocket is still part of the bucket, so keep counting it in expected.\nThe reallocations are sized from expected, and a request sock whose\nrefcount gets published while the lock is held across the last realloc\nmust already have room.\n\nA skipped socket is counted in expected but never batched, so end_sk\ncan be short of expected on a batch that is actually complete. Decide\ncompleteness by whether the walk left any socket behind instead. The\nWARN after the locked realloc checks the same, replacing an\nend_sk == expected check that could not hold on that path since\ncommit cdec67a489d4 (\"bpf: tcp: Make sure iter->batch always\ncontains a full bucket snapshot\").\n\nIf every matching socket in a bucket is mid-init (refcount 0), end_sk\nstays 0. Advance to the next bucket rather than returning a batch entry\nthat was never filled this round."
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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 - bpf_iter_tcp_established_batch() is reached only via local bpf() to load a BPF_TRACE_ITER TCP program, create an iterator link/fd, and read() it (bpf_seq_read->bpf_iter_tcp_batch); per kernel CNA guidance BPF iterator paths are Local even though concurrent TCP_NEW_SYN_RECV creation can be driven by network SYNs.\nAC:L - The fix commit reproduces in seconds with threads doing connect()/close() while others read iter/tcp in a tight loop; the attacker controls both the BPF iterator and TCP connection churn, so the refcount race between sock_hold() and refcount_set() is reliably winnable without uncontrollable victim state.\nPR:L - Loading BPF_PROG_TYPE_TRACING/BPF_TRACE_ITER requires CAP_BPF and CAP_PERFMON at bpf_prog_load(); per kernel CNA guidance these are Low privileges because BPF tokens and user namespaces can delegate them to non-init-namespace users, not only real root.\nUI:N - No victim interaction is required; the attacker loads their own iter/tcp BPF program and link, then triggers the race with self-generated connect/close traffic or SYN activity to listeners in the iterated network namespace.\nS:U - Impact is a kernel heap use-after-free and memory corruption within the same host kernel security authority; this is standard local kernel compromise/crash, not a VM escape, sandbox boundary cross, or IOMMU bypass.\nC:H - The iterator retains dangling request_sock pointers after refcount_set() clobbers a sock_hold() taken on sk_refcnt==0; subsequent bpf_iter_tcp_seq_show/put_batch dereference freed kernel objects, giving UAF read primitives per kernel CNA UAF guidance.\nI:H - Freed request_sock slabs can be reallocated while the iterator batch still references them; UAF enables corrupted socket metadata, refcount abuse, and control-flow hijacking via heap grooming, meeting High integrity under kernel CNA memory-corruption guidance.\nA:H - The bug surfaces as refcount_warn_saturate and leaves the reqsk one reference short so it is freed while still reachable from the iterator batch, causing kernel oops/panic; the tight-loop repro shows reliable, repeatable host denial of service."
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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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"net/ipv4/tcp_ipv4.c"
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],
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"versions": [
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{
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"version": "04c7820b776f1c4b48698574c47de9e940d368e8",
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"lessThan": "cc0295f89296ed351fc4b0b48fee887ba02c5d24",
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"status": "affected",
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"versionType": "git"
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"version": "04c7820b776f1c4b48698574c47de9e940d368e8",
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"lessThan": "ddbe966b5d1fe212ada749bc3d0b410f1a7dea74",
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"status": "affected",
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"version": "04c7820b776f1c4b48698574c47de9e940d368e8",
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"lessThan": "97e74d3e45d653c07c2d406fc530a9bbe3df8396",
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{
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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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"net/ipv4/tcp_ipv4.c"
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],
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"versions": [
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{
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"version": "5.15",
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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": "5.15",
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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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},
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{
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"version": "6.6.152",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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},
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{
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"version": "6.12.104",
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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": "6.18.45",
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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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"references": [
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{
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"url": "https://git.kernel.org/stable/c/cc0295f89296ed351fc4b0b48fee887ba02c5d24"
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},
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"url": "https://git.kernel.org/stable/c/ddbe966b5d1fe212ada749bc3d0b410f1a7dea74"
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"url": "https://git.kernel.org/stable/c/7d2b60a4bc0499f62ff8520af6309bbe170882fd"
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"url": "https://git.kernel.org/stable/c/cefcbbe20846a45f9a7dae868f7ef1000953e2df"
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"url": "https://git.kernel.org/stable/c/97e74d3e45d653c07c2d406fc530a9bbe3df8396"
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"url": "https://git.kernel.org/stable/c/e5fd3f514e27db1f05fbd72ba615d74941e23c51"
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}
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],
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"title": "bpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch()",
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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-2026-74714",
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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": "2026-10-16T19:15:26.338787Z"
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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": "2026-10-16T19:16:11.358Z"
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}
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}
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]
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}
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} |