CVE-2026-64588 (GCVE-0-2026-64588)

Vulnerability from cvelistv5 – Published: 2026-08-06 07:13 – Updated: 2026-08-08 15:13
VLAI
Title
fuse-uring: fix data races on ring->ready
Summary
In the Linux kernel, the following vulnerability has been resolved: fuse-uring: fix data races on ring->ready On weakly-ordered architectures, the store to fiq->ops can be reordered past the store to ring->ready, allowing a CPU that sees ring->ready == true via fuse_uring_ready() to dispatch requests through a stale fiq->ops pointer. Upgrade the store to smp_store_release() and the load in fuse_uring_ready() to smp_load_acquire() so that the preceding WRITE_ONCE(fiq->ops, ...) is visible to any CPU that observes ring->ready == true. Additionally, fuse_uring_do_register() publishes ring->ready with WRITE_ONCE() but the fast-path check reads it with a plain load. This is a marked-vs-unmarked access that KCSAN will flag. Wrap it in READ_ONCE() to mark it without adding unnecessary ordering. Also wrap the fc->ring load in fuse_uring_ready() in READ_ONCE() to prevent the compiler from reloading it between the NULL check and the dereference.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < b156bb9966972122b148acab8bdf415cdb8176a3 (git)
Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < d01a09b442cb786cd44ccc7c84d57e2856d6737c (git)
Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < 46725a0056c884cf58a6897f222892807327d82d (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/dev_uring.c",
            "fs/fuse/dev_uring_i.h"
          ],
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              "version": "6.14"
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              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
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                  "versionStartIncluding": "6.14",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.14",
                  "vulnerable": true
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: fix data races on ring-\u003eready\n\nOn weakly-ordered architectures, the store to fiq-\u003eops can be\nreordered past the store to ring-\u003eready, allowing a CPU that sees\nring-\u003eready == true via fuse_uring_ready() to dispatch requests\nthrough a stale fiq-\u003eops pointer. Upgrade the store to\nsmp_store_release() and the load in fuse_uring_ready() to\nsmp_load_acquire() so that the preceding WRITE_ONCE(fiq-\u003eops, ...)\nis visible to any CPU that observes ring-\u003eready == true.\n\nAdditionally, fuse_uring_do_register() publishes ring-\u003eready with\nWRITE_ONCE() but the fast-path check reads it with a plain load.\nThis is a marked-vs-unmarked access that KCSAN will flag. Wrap it in\nREAD_ONCE() to mark it without adding unnecessary ordering.\n\nAlso wrap the fc-\u003ering load in fuse_uring_ready() in READ_ONCE() to\nprevent the compiler from reloading it between the NULL check and the\ndereference."
        }
      ],
      "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 bug is reached locally by mounting FUSE with io-uring and submitting IORING_OP_URING_CMD registration while other local threads generate FUSE requests; no network protocol path invokes fuse_uring_ready() or fuse_uring_do_register().\nAC:L - The attacker controls both sides of the race by registering ring entries on /dev/fuse while concurrently issuing filesystem operations on the same mount, so the publish window on weakly ordered CPUs can be driven and retried without relying on victim state.\nPR:L - FUSE is FS_USERNS_MOUNT, so an ordinary user can create a user-namespace mount, open /dev/fuse, and enable FUSE_OVER_IO_URING without init-namespace root privileges.\nUI:N - The attacker can run both the FUSE daemon that registers io-uring queues and the client threads that generate requests on that mount, so no separate victim action is required.\nS:U - Impact is confined to the host kernel authority as a local FUSE/io-uring memory-safety failure, not a VM, IOMMU, or guest-to-host boundary escape.\nC:H - Missing acquire on ring-\u003eready lets CPUs observe readiness while fiq-\u003eops and related ring publication are stale, and the unfixed fc-\u003ering reload in fuse_uring_ready() is a check-then-use UAF window against ring teardown, enabling disclosure of reclaimed kernel memory.\nI:H - Dispatching through inconsistent ops/ring state and the concurrent ring reload UAF allow writes and list/queue operations on stale or reallocated fuse_ring objects, which is exploitable for heap corruption and control-flow hijacking.\nA:H - The same races can NULL-dereference or use a freed fuse_ring in fuse_uring_task_to_queue()/fuse_uring_ready(), hang requests on the wrong queue path, and trigger WARN/oops or panic under panic_on_warn."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-08T15:13:25.994Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/b156bb9966972122b148acab8bdf415cdb8176a3"
        },
        {
          "url": "https://git.kernel.org/stable/c/d01a09b442cb786cd44ccc7c84d57e2856d6737c"
        },
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          "url": "https://git.kernel.org/stable/c/46725a0056c884cf58a6897f222892807327d82d"
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      "title": "fuse-uring: fix data races on ring-\u003eready",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64588",
    "datePublished": "2026-08-06T07:13:46.688Z",
    "dateReserved": "2026-07-19T15:36:31.798Z",
    "dateUpdated": "2026-08-08T15:13:25.994Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-08-08",
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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