CVE-2025-40047 (GCVE-0-2025-40047)
Vulnerability from cvelistv5
Published
2025-10-28 11:48
Modified
2026-08-05 12:07
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/waitid: always prune wait queue entry in io_waitid_wait() For a successful return, always remove our entry from the wait queue entry list. Previously this was skipped if a cancelation was in progress, but this can race with another invocation of the wait queue entry callback.
References
Impacted products
Vendor Product Version
Linux Linux Version: f31ecf671ddc498f20219453395794ff2383e06b
Version: f31ecf671ddc498f20219453395794ff2383e06b
Version: f31ecf671ddc498f20219453395794ff2383e06b
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/waitid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "696ba6032081e617564a8113a001b8d7943cb928",
              "status": "affected",
              "version": "f31ecf671ddc498f20219453395794ff2383e06b",
              "versionType": "git"
            },
            {
              "lessThan": "3e2205db2f0608898d535da1964e1b376aacfdaa",
              "status": "affected",
              "version": "f31ecf671ddc498f20219453395794ff2383e06b",
              "versionType": "git"
            },
            {
              "lessThan": "2f8229d53d984c6a05b71ac9e9583d4354e3b91f",
              "status": "affected",
              "version": "f31ecf671ddc498f20219453395794ff2383e06b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/waitid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.53",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.3",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/waitid: always prune wait queue entry in io_waitid_wait()\n\nFor a successful return, always remove our entry from the wait queue\nentry list. Previously this was skipped if a cancelation was in\nprogress, but this can race with another invocation of the wait queue\nentry callback."
        }
      ],
      "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 vulnerability is reached through the io_uring syscall interface (`io_uring_setup`/`io_uring_enter` submitting an `IORING_OP_WAITID` SQE) plus process-management signals, all of which require local access to the system. Per kernel scoring guidance, io_uring bugs are Local.\nAC:L - The attacker controls both sides of the race: it drives the wait-queue wakeups at arbitrary rate by forking children and looping SIGSTOP/SIGCONT (`do_notify_parent_cldstop` \u2192 `__wake_up_parent`), while concurrently submitting `IORING_OP_ASYNC_CANCEL` or tearing down the ring from another thread to grab the competing reference. syzbot produced a working reproducer and confirmed the fix, showing the window is hit reliably.\nPR:L - Any unprivileged local user can create an io_uring ring \u2014 `sysctl_io_uring_disabled` defaults to 0 and `IORING_OP_WAITID` carries no capability check \u2014 and waiting on one\u0027s own forked children needs no privilege at all. No capabilities, user namespaces, or root are required.\nUI:N - The attacker\u0027s own process performs every step: submitting the waitid SQE, forking and signalling the children that generate wakeups, and issuing the concurrent cancel. No action by any other user is needed.\nS:U - The use-after-free corrupts kernel heap memory and control flow within the same kernel security authority, yielding standard local privilege escalation. No VM, IOMMU, or other security-boundary crossing is involved.\nC:H - This is a use-after-free on a `struct io_waitid_async` allocated from a general-purpose kmalloc slab, which the attacker can reclaim and shape via heap spraying. The stale wait-queue entry is then dereferenced by `__wake_up_common()` and `list_del_init()`, giving a read primitive over reclaimed kernel memory that can be leveraged for arbitrary kernel memory disclosure.\nI:H - `list_del_init()` on the freed entry performs `prev-\u003enext = next; next-\u003eprev = prev` using pointers read from attacker-reclaimed memory, yielding a controlled write of a controlled pointer to a controlled address. Additionally `__wake_up_common()` calls `curr-\u003efunc(...)` on the freed entry, providing a direct indirect-call/control-flow hijack primitive leading to kernel code execution.\nA:H - Even without weaponization, the dangling wait-queue entry and the list-corrupting `list_del_init()` on freed memory produce KASAN splats, list debug BUGs, and kernel oopses/panics \u2014 this is exactly how syzbot detected it. The race can be re-triggered in a tight loop, so an unprivileged user can crash the machine at will."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:07:20.600Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/696ba6032081e617564a8113a001b8d7943cb928"
        },
        {
          "url": "https://git.kernel.org/stable/c/3e2205db2f0608898d535da1964e1b376aacfdaa"
        },
        {
          "url": "https://git.kernel.org/stable/c/2f8229d53d984c6a05b71ac9e9583d4354e3b91f"
        }
      ],
      "title": "io_uring/waitid: always prune wait queue entry in io_waitid_wait()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40047",
    "datePublished": "2025-10-28T11:48:24.625Z",
    "dateReserved": "2025-04-16T07:20:57.156Z",
    "dateUpdated": "2026-08-05T12:07:20.600Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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