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

Vulnerability from cvelistv5 – Published: 2026-08-06 07:13 – Updated: 2026-08-17 04:58
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 CPE status
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 , ≤ * (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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          "vendor": "Linux",
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              "negate": false,
              "operator": "OR"
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        {
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          "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."
        }
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            "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"
          },
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              "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."
            }
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        "dateUpdated": "2026-08-17T04:58:09.400Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/d01a09b442cb786cd44ccc7c84d57e2856d6737c"
        },
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          "url": "https://git.kernel.org/stable/c/46725a0056c884cf58a6897f222892807327d82d"
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    "cveId": "CVE-2026-64588",
    "datePublished": "2026-08-06T07:13:46.688Z",
    "dateReserved": "2026-07-19T15:36:31.798Z",
    "dateUpdated": "2026-08-17T04:58:09.400Z",
    "state": "PUBLISHED"
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            "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."
          }
        ],
        "id": "CVE-2026-64588",
        "lastModified": "2026-08-17T05:18:05.207",
        "metrics": {
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        "vulnStatus": "Received"
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      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-17T16:31:05Z",
      "cve": "CVE-2026-64588",
      "id": "CVE-2026-64588",
      "initial_release_date": "2026-08-06T23:55:51Z",
      "product_status:known_not_affected": "296",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64588",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64588.json",
      "version": "4"
    }
  }
}



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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.
  • 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.


Detection rules are retrieved from Rulezet.


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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.