CVE-2026-52933 (GCVE-0-2026-52933)
Vulnerability from cvelistv5
Published
2026-06-24 07:14
Modified
2026-08-05 12:31
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/poll: fix signed comparison in io_poll_get_ownership() io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath.
References
Impacted products
Vendor Product Version
Linux Linux Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: a26a35e9019fd70bf3cf647dcfdae87abc7bacea
Version: 4b702b7d11ce1b9d26fc6d7c5a7ef4ac1d455048
Version: bc4e6ee16778149811333a969a7a893d4cc110c5
Version: 5.15.82   ≤
Version: 6.0.11   ≤
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/poll.c"
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          "versions": [
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              "version": "6.1"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.1.175",
              "versionType": "semver"
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              "version": "6.6.140",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.12.86",
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.27",
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              "version": "7.0.4",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "versionEndExcluding": "6.1.175",
                  "versionStartIncluding": "6.1",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/poll: fix signed comparison in io_poll_get_ownership()\n\nio_poll_get_ownership() uses a signed comparison to check whether\npoll_refs has reached the threshold for the slowpath:\n\n    if (unlikely(atomic_read(\u0026req-\u003epoll_refs) \u003e= IO_POLL_REF_BIAS))\n\natomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG\n(BIT(31)) is set in poll_refs, the value becomes negative in\nsigned arithmetic, so the \u003e= 128 comparison always evaluates to\nfalse and the slowpath is never taken.\n\nFix this by casting the atomic_read() result to unsigned int\nbefore the comparison, so that the cancel flag is treated as a\nlarge positive value and correctly triggers the slowpath."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable path is reached by local `io_uring_setup()`/`io_uring_enter()` submissions of poll and cancel operations, not by remote packets or physical access.\nAC:L - An attacker can create the ring, choose pollable file descriptors, submit cancels/removes, and generate concurrent wakeups; the race participants are attacker-controlled.\nPR:L - With the default `io_uring_disabled=0`, an unprivileged local user can create and use io_uring; no real root or init-namespace capability is required.\nUI:N - Exploitation does not require another user to mount, open, or process anything; the attacker drives the syscall and file-descriptor activity directly.\nS:U - This is a kernel request-lifetime/ownership bug within the same host kernel security authority, not a VM, IOMMU, or separate security-scope escape.\nC:H - The signedness bug defeats the poll_refs overflow/ownership slow path after cancellation, allowing ref-bit wrap and duplicate ownership/completion of an `io_kiocb`; that is UAF-style kernel memory corruption with plausible memory disclosure.\nI:H - The same duplicate ownership/completion and request lifetime corruption can plausibly be shaped into arbitrary kernel memory modification or control-flow compromise, so integrity impact is high.\nA:H - At minimum, corrupted poll ownership and duplicate completion can trigger kernel warnings, NULL dereferences, UAF crashes, or hangs in a local attacker-controlled loop."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:31:51.192Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3"
        },
        {
          "url": "https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763"
        },
        {
          "url": "https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18"
        },
        {
          "url": "https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5"
        },
        {
          "url": "https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae"
        },
        {
          "url": "https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42"
        }
      ],
      "title": "io_uring/poll: fix signed comparison in io_poll_get_ownership()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-52933",
    "datePublished": "2026-06-24T07:14:24.678Z",
    "dateReserved": "2026-06-09T07:44:35.369Z",
    "dateUpdated": "2026-08-05T12:31:51.192Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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