Vulnerability-Lookup

GHSA-C86R-6X5C-X35M

Vulnerability from github – Published: 2026-11-03 12:31 – Updated: 2026-11-03 21:32

Details

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

io_uring/cancel: rearm local work wake up before sleep

io_uring_try_cancel_requests() sets ->cq_wait_nr to 1 so that the next io_req_local_work_add() wakes the cancelling task. The add that takes the count to zero is the only one that wakes, later ones see a count <= 0 and return. io_uring_cancel_generic() however only becomes TASK_INTERRUPTIBLE much later, so the one wake up can be spent on a running task. That is fine as long as the entry of that add is still queued, as the io_local_work_pending() check then skips the sleep. It is not if the add was delayed after queueing its entry:

CPU0 (submitter in exec or exit) CPU1 (io_req_local_work_add) mpscq_push(req A) io_uring_try_cancel_requests() io_run_local_work() // runs req A io_uring_try_cancel_requests() atomic_set(&ctx->cq_wait_nr, 1) atomic_read(&ctx->cq_wait_nr) == 1 count taken, wake_up_state() // task is running, no-op prepare_to_wait(TASK_INTERRUPTIBLE) io_local_work_pending() == false schedule() mpscq_push(req B) cq_wait_nr <= 0, return

Only the sleeping task can run req B, so it is stuck in execve() until a signal happens to wake it. An exiting task doesn't even get that.

Arm the count again once the task state is set and before the work list is checked, for the rings whose local work this task is the one to run.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-99253"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-11-03T12:17:32Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/cancel: rearm local work wake up before sleep\n\nio_uring_try_cancel_requests() sets -\u003ecq_wait_nr to 1 so that the next\nio_req_local_work_add() wakes the cancelling task. The add that takes the\ncount to zero is the only one that wakes, later ones see a count \u003c= 0 and\nreturn. io_uring_cancel_generic() however only becomes\nTASK_INTERRUPTIBLE much later, so the one wake up can be spent on a\nrunning task. That is fine as long as the entry of that add is still\nqueued, as the io_local_work_pending() check then skips the sleep. It is\nnot if the add was delayed after queueing its entry:\n\nCPU0 (submitter in exec or exit)      CPU1 (io_req_local_work_add)\n                                      mpscq_push(req A)\nio_uring_try_cancel_requests()\n  io_run_local_work()  // runs req A\nio_uring_try_cancel_requests()\n  atomic_set(\u0026ctx-\u003ecq_wait_nr, 1)\n                                      atomic_read(\u0026ctx-\u003ecq_wait_nr) == 1\n                                      count taken, wake_up_state()\n                                        // task is running, no-op\nprepare_to_wait(TASK_INTERRUPTIBLE)\nio_local_work_pending() == false\nschedule()\n                                      mpscq_push(req B)\n                                      cq_wait_nr \u003c= 0, return\n\nOnly the sleeping task can run req B, so it is stuck in execve() until a\nsignal happens to wake it. An exiting task doesn\u0027t even get that.\n\nArm the count again once the task state is set and before the work list\nis checked, for the rings whose local work this task is the one to run.",
  "id": "GHSA-c86r-6x5c-x35m",
  "modified": "2026-11-03T21:32:06Z",
  "published": "2026-11-03T12:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99253"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/76a82c666abf155ad52d5f41043eac77dd3e41d8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-99253 (GCVE-0-2026-99253)

Vulnerability from cvelistv5 – Published: 2026-11-03 11:20 – Updated: 2026-11-03 19:13

Title

io_uring/cancel: rearm local work wake up before sleep

Summary

In the Linux kernel, the following vulnerability has been resolved: io_uring/cancel: rearm local work wake up before sleep io_uring_try_cancel_requests() sets ->cq_wait_nr to 1 so that the next io_req_local_work_add() wakes the cancelling task. The add that takes the count to zero is the only one that wakes, later ones see a count <= 0 and return. io_uring_cancel_generic() however only becomes TASK_INTERRUPTIBLE much later, so the one wake up can be spent on a running task. That is fine as long as the entry of that add is still queued, as the io_local_work_pending() check then skips the sleep. It is not if the add was delayed after queueing its entry: CPU0 (submitter in exec or exit) CPU1 (io_req_local_work_add) mpscq_push(req A) io_uring_try_cancel_requests() io_run_local_work() // runs req A io_uring_try_cancel_requests() atomic_set(&ctx->cq_wait_nr, 1) atomic_read(&ctx->cq_wait_nr) == 1 count taken, wake_up_state() // task is running, no-op prepare_to_wait(TASK_INTERRUPTIBLE) io_local_work_pending() == false schedule() mpscq_push(req B) cq_wait_nr <= 0, return Only the sleeping task can run req B, so it is stuck in execve() until a signal happens to wake it. An exiting task doesn't even get that. Arm the count again once the task state is set and before the work list is checked, for the rings whose local work this task is the one to run.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

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

References

2 references

URL	Tags
https://git.kernel.org/stable/c/aaa06bb9fc03384f7…
https://git.kernel.org/stable/c/76a82c666abf155ad…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d46ab2c98ababa19b41a5709b6921d7b1add7f74 , < aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2 (git) Affected: d46ab2c98ababa19b41a5709b6921d7b1add7f74 , < 76a82c666abf155ad52d5f41043eac77dd3e41d8 (git)
Linux	Linux	Affected: 7.2 Unaffected: 0 , < 7.2 (semver) Unaffected: 7.2.14 , ≤ 7.2.* (semver) Unaffected: 7.4-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/cancel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2",
              "status": "affected",
              "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
              "versionType": "git"
            },
            {
              "lessThan": "76a82c666abf155ad52d5f41043eac77dd3e41d8",
              "status": "affected",
              "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/cancel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.4-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.14",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.4-rc1",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/cancel: rearm local work wake up before sleep\n\nio_uring_try_cancel_requests() sets -\u003ecq_wait_nr to 1 so that the next\nio_req_local_work_add() wakes the cancelling task. The add that takes the\ncount to zero is the only one that wakes, later ones see a count \u003c= 0 and\nreturn. io_uring_cancel_generic() however only becomes\nTASK_INTERRUPTIBLE much later, so the one wake up can be spent on a\nrunning task. That is fine as long as the entry of that add is still\nqueued, as the io_local_work_pending() check then skips the sleep. It is\nnot if the add was delayed after queueing its entry:\n\nCPU0 (submitter in exec or exit)      CPU1 (io_req_local_work_add)\n                                      mpscq_push(req A)\nio_uring_try_cancel_requests()\n  io_run_local_work()  // runs req A\nio_uring_try_cancel_requests()\n  atomic_set(\u0026ctx-\u003ecq_wait_nr, 1)\n                                      atomic_read(\u0026ctx-\u003ecq_wait_nr) == 1\n                                      count taken, wake_up_state()\n                                        // task is running, no-op\nprepare_to_wait(TASK_INTERRUPTIBLE)\nio_local_work_pending() == false\nschedule()\n                                      mpscq_push(req B)\n                                      cq_wait_nr \u003c= 0, return\n\nOnly the sleeping task can run req B, so it is stuck in execve() until a\nsignal happens to wake it. An exiting task doesn\u0027t even get that.\n\nArm the count again once the task state is set and before the work list\nis checked, for the rings whose local work this task is the one to run."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-03T19:13:12.605Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2"
        },
        {
          "url": "https://git.kernel.org/stable/c/76a82c666abf155ad52d5f41043eac77dd3e41d8"
        }
      ],
      "title": "io_uring/cancel: rearm local work wake up before sleep",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99253",
    "datePublished": "2026-11-03T11:20:12.490Z",
    "dateReserved": "2026-09-25T10:25:14.403Z",
    "dateUpdated": "2026-11-03T19:13:12.605Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted