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CVE-2026-68283 (GCVE-0-2026-68283)

Vulnerability from cvelistv5 – Published: 2026-08-10 12:02 – Updated: 2026-08-17 05:02
VLAI
Title
tracing: Fix use-after-free freeing trigger private data
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix use-after-free freeing trigger private data Commit 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event_trigger_data") moved the kfree() of event_trigger_data to a kthread that runs tracepoint_synchronize_unregister() before freeing. That removed the synchronization the trigger .free callbacks used to get implicitly and inline from trigger_data_free(). event_hist_trigger_free(), event_hist_trigger_named_free() and event_enable_trigger_free() free their satellite data (hist_data, cmd_ops, enable_data) right after trigger_data_free() returns. With the synchronization now deferred to the kthread, a concurrent tracepoint handler can still reach that data through the list_del_rcu()'d trigger, causing a use-after-free. The histogram teardown must stay synchronous: remove_hist_vars() and unregister_field_var_hists() have to detach a synthetic event from the histogram before the trigger-removal write returns, otherwise a following command races in and the synthetic-event removal fails with -EBUSY, as the trigger-synthetic-eprobe.tc selftest catches. Make those callbacks wait with the correct barrier - tracepoint_synchronize_unregister(), matching the free kthread - before freeing. The enable trigger has no such synchronous requirement, and a blocking synchronize there would re-serialize the path that commit deliberately deferred. Give it an optional private_data_free() callback that the free kthread runs after its grace period, and free enable_data from there.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 61d445af0a7c70018111919e47beaaee15653f2f , < b9c8a1400a3bf633f32820d184f3e05fed0f4af7 (git)
Affected: 61d445af0a7c70018111919e47beaaee15653f2f , < 79097812153b826fc156a2930ec8a90ed9edf4a2 (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace.h",
            "kernel/trace/trace_events_hist.c",
            "kernel/trace/trace_events_trigger.c"
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          "versions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix use-after-free freeing trigger private data\n\nCommit 61d445af0a7c (\"tracing: Add bulk garbage collection of freeing\nevent_trigger_data\") moved the kfree() of event_trigger_data to a kthread\nthat runs tracepoint_synchronize_unregister() before freeing. That removed\nthe synchronization the trigger .free callbacks used to get implicitly and\ninline from trigger_data_free().\n\nevent_hist_trigger_free(), event_hist_trigger_named_free() and\nevent_enable_trigger_free() free their satellite data (hist_data, cmd_ops,\nenable_data) right after trigger_data_free() returns. With the\nsynchronization now deferred to the kthread, a concurrent tracepoint\nhandler can still reach that data through the list_del_rcu()\u0027d trigger,\ncausing a use-after-free.\n\nThe histogram teardown must stay synchronous: remove_hist_vars() and\nunregister_field_var_hists() have to detach a synthetic event from the\nhistogram before the trigger-removal write returns, otherwise a following\ncommand races in and the synthetic-event removal fails with -EBUSY, as the\ntrigger-synthetic-eprobe.tc selftest catches. Make those callbacks wait\nwith the correct barrier - tracepoint_synchronize_unregister(), matching\nthe free kthread - before freeing.\n\nThe enable trigger has no such synchronous requirement, and a blocking\nsynchronize there would re-serialize the path that commit deliberately\ndeferred. Give it an optional private_data_free() callback that the free\nkthread runs after its grace period, and free enable_data from there."
        }
      ],
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "value": "AV:N - Placeholder.\nAC:L - The attacker controls both sides of the race: one thread writes \u0027!hist:\u0027/\u0027!enable_event:\u0027 to remove the trigger while another continuously fires the traced event, so an in-flight event_triggers_call() reader reliably touches hist_data/enable_data after they are freed inline.\nPR:L - Registering and removing triggers only needs write access to tracefs (TRACE_MODE_WRITE, DAC plus LOCKDOWN_TRACEFS, no capable() gate), which realistic deployments such as Android/perfetto, ChromeOS and gid=tracing mounts grant to unprivileged tracing users.\nUI:N - The attacker performs both the trigger removal and the event generation itself; no separate victim action is required.\nS:U - The use-after-free corrupts kernel heap memory within the same OS security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - A concurrent handler dereferences the freed hist_trigger_data (n_keys, fields[], key_size, tracing_map) and the freed enable_trigger_data-\u003efile, so reclaimed heap contents are read and can be reflected back through histogram output, giving arbitrary kernel memory disclosure.\nI:H - event_hist_trigger() writes into freed tracing_map elements and event_enable_trigger() writes event-file flags through a pointer read from freed enable_data, so heap spraying the reclaimed objects yields a controlled write primitive suitable for privilege escalation.\nA:H - Use-after-free of hist_data/cmd_ops/enable_data readily causes oops or panic in tracepoint context even without successful exploitation, and the race can be re-triggered at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:02:18.147Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/b9c8a1400a3bf633f32820d184f3e05fed0f4af7"
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        {
          "url": "https://git.kernel.org/stable/c/79097812153b826fc156a2930ec8a90ed9edf4a2"
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      "title": "tracing: Fix use-after-free freeing trigger private data",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68283",
    "datePublished": "2026-08-10T12:02:15.088Z",
    "dateReserved": "2026-07-30T09:28:09.379Z",
    "dateUpdated": "2026-08-17T05:02:18.147Z",
    "state": "PUBLISHED"
  },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-31T11:20:58+00:00",
      "cve": "CVE-2026-68283",
      "id": "CVE-2026-68283",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_not_affected": "277",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: tracing: Fix use-after-free freeing trigger private data",
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      "current_release_date": "2026-09-15T01:37:15Z",
      "cve": "CVE-2026-68283",
      "id": "CVE-2026-68283",
      "initial_release_date": "2026-08-22T00:54:58Z",
      "product_status:known_affected": "374",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68283",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68283.json",
      "version": "4"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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