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GHSA-2CPV-4F6V-PR9H

Vulnerability from github – Published: 2026-11-02 18:32 – Updated: 2026-11-03 21:31

Details

In the Linux kernel, the following vulnerability has been resolved:

coredump: hold RCU while releasing parked threads

coredump_finish() releases the parked threads by clearing ->task in their core_thread entry and calling wake_up_process() on each of them. It does that without holding a reference on the task and without being inside rcu.

But calling wake_up_process(task) without rcu here isn't safe. A parked thread doesn't need that wakeup to leave. A spurious wakeup or a preemption after the store is enough for the task to go away.

So if the coredump client is preempted between the store and wake_up_process() the thread can exit and be freed in the meantime and try_to_wake_up() takes pi_lock in freed memory.

Hold rcu across the loop.

Severity

7.0 (High)


                  
                    CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-99218"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-11-02T16:17:45Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncoredump: hold RCU while releasing parked threads\n\ncoredump_finish() releases the parked threads by clearing -\u003etask in\ntheir core_thread entry and calling wake_up_process() on each of them.\nIt does that without holding a reference on the task and without being\ninside rcu.\n\nBut calling wake_up_process(task) without rcu here isn\u0027t safe. A parked\nthread doesn\u0027t need that wakeup to leave. A spurious wakeup or a\npreemption after the store is enough for the task to go away.\n\nSo if the coredump client is preempted between the store and\nwake_up_process() the thread can exit and be freed in the meantime and\ntry_to_wake_up() takes pi_lock in freed memory.\n\nHold rcu across the loop.",
  "id": "GHSA-2cpv-4f6v-pr9h",
  "modified": "2026-11-03T21:31:58Z",
  "published": "2026-11-02T18:32:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99218"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0fce73efee40c65ce26641c5d93942462f9e8307"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/16e94ed90b1b02398e044d41fd1db34828daa08e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/61d58591aa0188bf2463e263962256316ff8b576"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/71146c437bae59e5280f657965dc6d006ee3989b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a0f09ff4c6b93312e565cfe75d76c3a551a3ec4c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b0eca0edddf4c1dbaf6d1f6a8636b4235f5bc573"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fd0fbe84312fda2fc187428c92c50b7d03a9d24c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-99218 (GCVE-0-2026-99218)

Vulnerability from cvelistv5 – Published: 2026-11-02 16:06 – Updated: 2026-11-03 19:12

Title

coredump: hold RCU while releasing parked threads

Summary

In the Linux kernel, the following vulnerability has been resolved: coredump: hold RCU while releasing parked threads coredump_finish() releases the parked threads by clearing ->task in their core_thread entry and calling wake_up_process() on each of them. It does that without holding a reference on the task and without being inside rcu. But calling wake_up_process(task) without rcu here isn't safe. A parked thread doesn't need that wakeup to leave. A spurious wakeup or a preemption after the store is enough for the task to go away. So if the coredump client is preempted between the store and wake_up_process() the thread can exit and be freed in the meantime and try_to_wake_up() takes pi_lock in freed memory. Hold rcu across the loop.

Severity

7 (High)


                        
                          CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6637 records in the last 180 days details

References

7 references

URL	Tags
https://git.kernel.org/stable/c/fd0fbe84312fda2fc…
https://git.kernel.org/stable/c/71146c437bae59e52…
https://git.kernel.org/stable/c/0fce73efee40c65ce…
https://git.kernel.org/stable/c/16e94ed90b1b02398…
https://git.kernel.org/stable/c/a0f09ff4c6b93312e…
https://git.kernel.org/stable/c/b0eca0edddf4c1dba…
https://git.kernel.org/stable/c/61d58591aa0188bf2…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < fd0fbe84312fda2fc187428c92c50b7d03a9d24c (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < 71146c437bae59e5280f657965dc6d006ee3989b (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < 0fce73efee40c65ce26641c5d93942462f9e8307 (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < 16e94ed90b1b02398e044d41fd1db34828daa08e (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < a0f09ff4c6b93312e565cfe75d76c3a551a3ec4c (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < b0eca0edddf4c1dbaf6d1f6a8636b4235f5bc573 (git) Affected: a94e2d408eaedbd85aae259621d46fafc10479a2 , < 61d58591aa0188bf2463e263962256316ff8b576 (git)
Linux	Linux	Affected: 2.6.27 Unaffected: 0 , < 2.6.27 (semver) Unaffected: 6.1.191 , ≤ 6.1.* (semver) Unaffected: 6.6.161 , ≤ 6.6.* (semver) Unaffected: 6.12.115 , ≤ 6.12.* (semver) Unaffected: 6.18.60 , ≤ 6.18.* (semver) Unaffected: 7.2.14 , ≤ 7.2.* (semver) Unaffected: 7.3.1 , ≤ 7.3.* (semver) Unaffected: 7.4-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/coredump.c"
          ],
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          "vendor": "Linux",
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              "status": "affected",
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              "versionType": "git"
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              "status": "affected",
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            },
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              "versionType": "git"
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              "versionType": "git"
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          "versions": [
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              "version": "2.6.27"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.6.161",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.12.115",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.60",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.2.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.3.*",
              "status": "unaffected",
              "version": "7.3.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.4-rc1",
              "versionType": "original_commit_for_fix"
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        }
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      "cpeApplicability": [
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          "nodes": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncoredump: hold RCU while releasing parked threads\n\ncoredump_finish() releases the parked threads by clearing -\u003etask in\ntheir core_thread entry and calling wake_up_process() on each of them.\nIt does that without holding a reference on the task and without being\ninside rcu.\n\nBut calling wake_up_process(task) without rcu here isn\u0027t safe. A parked\nthread doesn\u0027t need that wakeup to leave. A spurious wakeup or a\npreemption after the store is enough for the task to go away.\n\nSo if the coredump client is preempted between the store and\nwake_up_process() the thread can exit and be freed in the meantime and\ntry_to_wake_up() takes pi_lock in freed memory.\n\nHold rcu across the loop."
        }
      ],
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        {
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            "baseSeverity": "HIGH",
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          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is in coredump_finish(), reached when a local dump signal is delivered via get_signal() -\u003e vfs_coredump() -\u003e do_coredump()/coredump_cleanup(). abort(), a user page-fault SIGSEGV, or tgkill() on the attacker\u0027s own thread group starts that path; no remote protocol supplies the curr-\u003etask pointer later handed to wake_up_process().\nAC:H - coredump_wait() parks siblings in coredump_task_exit() in TASK_IDLE (no TASK_WAKEKILL), so kill/tgkill cannot wake them. The UAF needs the dumper preempted between curr-\u003etask=NULL and wake_up_process() long enough for a spurious or freezer wakeup, full do_exit(), and an RCU GP via delayed_put_task_struct() \u2014 timing the attacker cannot force.\nPR:L - get_signal() dumps the caller\u0027s own dumpable thread group with no capability check. An ordinary user pthread_create()s a sibling and abort()s or faults into vfs_coredump(); coredump_skip() only bails on TASK_DUMPABLE_OFF, which a normal user process is not.\nUI:N - The attacker creates the extra thread and delivers the dump signal inside their own process; no other user must mount media, open a file, or otherwise act.\nS:U - try_to_wake_up() on the freed task_struct corrupts host kernel scheduler state inside the same kernel; this is ordinary in-kernel UAF impact, not a VM, IOMMU, or sandbox escape.\nC:H - wake_up_process() -\u003e try_to_wake_up() reads __state, on_rq, and sched_class from the task_struct after delayed_put_task_struct() has freed it; a sprayable slab UAF read is High confidentiality per UAF guidance.\nI:H - try_to_wake_up() takes raw_spin_lock on the freed p-\u003epi_lock, writes __state, and calls p-\u003esched_class-\u003eenqueue_task(); reclaiming the task_struct slab yields a write and control-flow primitive.\nA:H - Taking pi_lock in memory already freed by delayed_put_task_struct(), as the fix describes, oopses or panics even without a successful spray, so availability is High."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-03T19:12:53.426Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        },
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          "url": "https://git.kernel.org/stable/c/61d58591aa0188bf2463e263962256316ff8b576"
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      "title": "coredump: hold RCU while releasing parked threads",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99218",
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    "dateReserved": "2026-09-25T10:25:14.401Z",
    "dateUpdated": "2026-11-03T19:12:53.426Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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