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vuln-cve/data/2026/89xxx/CVE-2026-89746.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-89746",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-09-11T19:38:34.762Z",
"datePublished": "2026-09-11T19:46:51.529Z",
"dateUpdated": "2026-10-19T08:52:00.175Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-19T08:52:00.175Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix use-after-free with same-name named triggers\n\nWhen two hist triggers on different events are registered with the same\nname=, the second one reuses the first as named_data. Both are added to\ntr->hist_vars by save_hist_vars() during event_hist_trigger_parse(),\nbecause save_hist_vars() is called before event_trigger_register() while\nthe named reuse is only detected later, in hist_register_trigger().\n\nIn the named-data branch hist_register_trigger() then frees the second\nhistogram's hist_data via destroy_hist_data(), but never removes its\ntr->hist_vars list entry, leaving a dangling pointer and leaking the\ntrace_array reference it holds.\n\nA later hist trigger that references a variable makes find_var_file()\nwalk tr->hist_vars and dereference the freed hist_data. The bug is\nreproducible from userspace by writing three hist triggers to tracefs:\n\n cd /sys/kernel/tracing\n echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_switch/trigger\n echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_process_fork/trigger\n echo 'hist:keys=common_pid:vals=$x' > events/sched/sched_process_exit/trigger\n\nThe third write panics the kernel:\n\n BUG: KASAN: slab-use-after-free in find_var_file.part.0+0x272/0x290\n Read of size 8 at addr ffff888001f8a0e0 by task sh/1\n CPU: 1 UID: 0 PID: 1 Comm: sh Tainted: G D N\n Call Trace:\n find_var_file.part.0\n find_event_var\n parse_atom\n parse_expr\n __create_val_field\n event_hist_trigger_parse\n trigger_process_regex\n event_trigger_write\n vfs_write\n ksys_write\n do_syscall_64\n entry_SYSCALL_64_after_hwframe\n Allocated by task 1:\n event_hist_trigger_parse\n Freed by task 1:\n hist_register_trigger+0x618/0xa30\n event_hist_trigger_parse\n The buggy address belongs to freed 2048-byte region\n Oops: general protection fault ... RIP: find_var_file.part.0\n Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b\n\nFix by removing the hist_data from tr->hist_vars and releasing the\ntrace_array reference in the named-data branch of hist_register_trigger()\nbefore freeing the hist_data."
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The UAF is reached only by writing hist trigger commands to tracefs event trigger files via write(2) (event_trigger_write -> event_hist_trigger_parse). There is no network, adjacent-radio, or physical-device path into hist_register_trigger() or find_var_file().\nAC:L - Triggering is fully deterministic: two sequential same-name named hist writes free hist_data while leaving it on tr->hist_vars, and a third vals=$x write walks that dangling pointer. No race or victim state is required, and CONFIG_HIST_TRIGGERS is standard in distro and Android kernels.\nPR:L - The path has no capable() check; event_trigger_open() only enforces LOCKDOWN_TRACEFS and DAC (TRACE_MODE_WRITE 0640). Tracefs is routinely delegated to non-root tracing users (Android/Perfetto, ChromeOS debugd, gid= tracing mounts), matching prior named-hist UAF scores (CVE-2025-21899).\nUI:N - The attacker performs all three trigger writes themselves; no victim action, mount, or cooperating process is required.\nS:U - The slab use-after-free corrupts kernel heap objects in the tracing subsystem within the same OS security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - find_var_file() and find_var_field() dereference the freed 2048-byte hist_trigger_data (event_file, fields[]). After reclaiming that slab, the attacker controls those pointers, and create_var_ref() persists var_field->hist_data for later tracing_map reads, yielding an arbitrary kernel read primitive.\nI:H - The dangling hist_vars entry plus a sprayed hist_trigger_data lets create_var_ref() store attacker-controlled hist_data/map pointers into the new trigger; event_hist_trigger()/resolve_var_refs() then write tracing_map state through those pointers, a heap write primitive suitable for control-flow hijack.\nA:H - The commit reproduces a KASAN slab-use-after-free in find_var_file() that oopses or panics the kernel (including killing init). Any use-after-free of hist_data is a reliable whole-system crash even without successful exploitation."
}
]
}
],
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"kernel/trace/trace_events_hist.c"
],
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"status": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
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],
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"status": "affected"
},
{
"version": "0",
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"status": "unaffected",
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},
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"lessThanOrEqual": "6.18.*",
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"lessThanOrEqual": "7.2.*",
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"versionType": "semver"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
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"nodes": [
{
"operator": "OR",
"negate": false,
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"references": [
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"url": "https://git.kernel.org/stable/c/441aa6742dff70297b5f64533a07a6189a026e91"
},
{
"url": "https://git.kernel.org/stable/c/3a8534664426c071c2dfb5b4ffa36b18a2abfd79"
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{
"url": "https://git.kernel.org/stable/c/477d762be4b0ffaf01429ccd88859e93b0ec28cc"
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{
"url": "https://git.kernel.org/stable/c/83d1ae0406d8eade219a81b401e201702dd9dc55"
},
{
"url": "https://git.kernel.org/stable/c/a7318172aa332a161fb9618286e64454c827f8fd"
}
],
"title": "tracing: Fix use-after-free with same-name named triggers",
"x_generator": {
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}
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