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CVE-2026-80920 (GCVE-0-2026-80920)

Vulnerability from cvelistv5 – Published: 2026-09-09 16:13 – Updated: 2026-09-09 16:13
VLAI
Title
io_uring: defer eventfd signaling when queued from a wakeup handler
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring: defer eventfd signaling when queued from a wakeup handler io_req_local_work_add() signals the CQ ring eventfd inline when it is the one to push the first entry onto ->work_list. For DEFER_TASKRUN rings that add is frequently done from a waitqueue wakeup handler, where an arbitrary waitqueue lock is held. eventfd_signal_mask() only refuses to recurse when current->in_eventfd is set, but that bit is set by eventfd_signal_mask() itself. If the wake chain starts somewhere else, signal goes out inline and can feed back into epoll. Add IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three waitqueue callbacks, and use it to force io_eventfd_signal() down the existing call_rcu_hurry() deferral instead of signaling inline.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < e22f4494cc9487d326e5e3067f33dea7c1e442b2 (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < 40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a (git)
Affected: 21a091b970cdbcf3e8ff829234b51be6f9192766 , < cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e (git)
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Linux Linux Affected: 6.1
Unaffected: 0 , < 6.1 (semver)
Unaffected: 6.18.49 , ≤ 6.18.* (semver)
Unaffected: 7.1.11 , ≤ 7.1.* (semver)
Unaffected: 7.2.1 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/io_uring_types.h",
            "io_uring/eventfd.c",
            "io_uring/eventfd.h",
            "io_uring/futex.c",
            "io_uring/io_uring.c",
            "io_uring/poll.c",
            "io_uring/tw.c",
            "io_uring/waitid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "21a091b970cdbcf3e8ff829234b51be6f9192766",
              "versionType": "git"
            },
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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          "defaultStatus": "affected",
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          "programFiles": [
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            "io_uring/eventfd.c",
            "io_uring/eventfd.h",
            "io_uring/futex.c",
            "io_uring/io_uring.c",
            "io_uring/poll.c",
            "io_uring/tw.c",
            "io_uring/waitid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.1"
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              "status": "unaffected",
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              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2.1",
              "versionType": "semver"
            },
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              "status": "unaffected",
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      "cpeApplicability": [
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          "nodes": [
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: defer eventfd signaling when queued from a wakeup handler\n\nio_req_local_work_add() signals the CQ ring eventfd inline when it is the\none to push the first entry onto -\u003ework_list. For DEFER_TASKRUN rings that\nadd is frequently done from a waitqueue wakeup handler, where an\narbitrary waitqueue lock is held.\n\neventfd_signal_mask() only refuses to recurse when current-\u003ein_eventfd\nis set, but that bit is set by eventfd_signal_mask() itself. If the wake\nchain starts somewhere else, signal goes out inline and can feed back\ninto epoll.\n\nAdd IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three\nwaitqueue callbacks, and use it to force io_eventfd_signal() down the\nexisting call_rcu_hurry() deferral instead of signaling inline."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-09T16:13:17.023Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/e22f4494cc9487d326e5e3067f33dea7c1e442b2"
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        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e"
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      "title": "io_uring: defer eventfd signaling when queued from a wakeup handler",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80920",
    "datePublished": "2026-09-09T16:13:17.023Z",
    "dateReserved": "2026-08-26T14:34:25.801Z",
    "dateUpdated": "2026-09-09T16:13:17.023Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-09-18",
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      "percentile": "0.05231"
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      "id": "msrc_CVE-2026-80920",
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "io_uring: defer eventfd signaling when queued from a wakeup handler",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-80920.json",
      "version": "1"
    },
    "nvd": {
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                  "io_uring/futex.c",
                  "io_uring/io_uring.c",
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          {
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: defer eventfd signaling when queued from a wakeup handler\n\nio_req_local_work_add() signals the CQ ring eventfd inline when it is the\none to push the first entry onto -\u003ework_list. For DEFER_TASKRUN rings that\nadd is frequently done from a waitqueue wakeup handler, where an\narbitrary waitqueue lock is held.\n\neventfd_signal_mask() only refuses to recurse when current-\u003ein_eventfd\nis set, but that bit is set by eventfd_signal_mask() itself. If the wake\nchain starts somewhere else, signal goes out inline and can feed back\ninto epoll.\n\nAdd IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three\nwaitqueue callbacks, and use it to force io_eventfd_signal() down the\nexisting call_rcu_hurry() deferral instead of signaling inline."
          }
        ],
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        "lastModified": "2026-09-09T17:17:47.120",
        "metrics": {},
        "published": "2026-09-09T17:17:47.120",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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      "current_release_date": "2026-09-10T16:27:27Z",
      "cve": "CVE-2026-80920",
      "id": "CVE-2026-80920",
      "initial_release_date": "2026-09-10T01:49:38Z",
      "product_status:known_affected": "114",
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      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80920",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80920.json",
      "version": "3"
    }
  }
}



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