CVE-2026-64262 (GCVE-0-2026-64262)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-07-25 08:49
VLAI
Title
fuse-uring: end fuse_req on io-uring cancel task work
Summary
In the Linux kernel, the following vulnerability has been resolved: fuse-uring: end fuse_req on io-uring cancel task work When io_uring delivers task work with tw.cancel set (PF_EXITING, PF_KTHREAD fallback, or percpu_ref_is_dying on the ring context), fuse_uring_send_in_task() takes the cancel branch, assigns -ECANCELED, and falls through to fuse_uring_send(). That path only flips the entry to FRRS_USERSPACE and completes the io_uring cmd; it never discharges the ring entry's owning reference to the fuse_req that fuse_uring_add_req_to_ring_ent() handed it at dispatch time. fuse_uring_send_in_task() tw.cancel == true err = -ECANCELED fuse_uring_send(ent, cmd, err, issue_flags) ent->state = FRRS_USERSPACE list_move(&ent->list, &queue->ent_in_userspace) ent->cmd = NULL io_uring_cmd_done(-ECANCELED) /* ent->fuse_req still set, req still hashed */ The fuse_req stays linked on fpq->processing[hash] and fuse_request_end() is never invoked. The originating syscall thread blocks in D-state in request_wait_answer() until fuse_abort_conn() runs, which can be the entire connection lifetime. For FR_BACKGROUND requests fc->num_background is never decremented either, so repeated cancels inflate the counter until max_background is hit and all later background ops stall. tw.cancel does not imply a connection abort (e.g. a single io_uring worker thread exits while the fuse connection stays up), so this cannot be left for fuse_abort_conn() to clean up. Ending the req but still routing the entry through fuse_uring_send() is not enough: that leaves a req-less entry on ent_in_userspace, and ent_list_request_expired() dereferences ent->fuse_req unconditionally on the head of that list, which would then NULL-deref. Fix the cancel branch to release the entry directly. Remove it from the queue, complete the io_uring cmd, end the fuse_req, free the entry, and drop its queue_refs (waking the teardown waiter if it was the last).
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7 (git)
Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < 4f45f276d5b4412eade6f74f2e37f3adba0473ed (git)
Affected: c2c9af9a0b13261c36909036057a116f2edb5e1a , < bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd (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": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fuse/dev_uring.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "6.14"
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            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "versionStartIncluding": "6.14",
                  "vulnerable": true
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                  "vulnerable": true
                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: end fuse_req on io-uring cancel task work\n\nWhen io_uring delivers task work with tw.cancel set (PF_EXITING,\nPF_KTHREAD fallback, or percpu_ref_is_dying on the ring context),\nfuse_uring_send_in_task() takes the cancel branch, assigns\n-ECANCELED, and falls through to fuse_uring_send(). That path only\nflips the entry to FRRS_USERSPACE and completes the io_uring cmd;\nit never discharges the ring entry\u0027s owning reference to the\nfuse_req that fuse_uring_add_req_to_ring_ent() handed it at\ndispatch time.\n\n    fuse_uring_send_in_task()\n      tw.cancel == true\n        err = -ECANCELED\n      fuse_uring_send(ent, cmd, err, issue_flags)\n        ent-\u003estate = FRRS_USERSPACE\n        list_move(\u0026ent-\u003elist, \u0026queue-\u003eent_in_userspace)\n        ent-\u003ecmd = NULL\n        io_uring_cmd_done(-ECANCELED)\n        /* ent-\u003efuse_req still set, req still hashed */\n\nThe fuse_req stays linked on fpq-\u003eprocessing[hash] and\nfuse_request_end() is never invoked. The originating syscall\nthread blocks in D-state in request_wait_answer() until\nfuse_abort_conn() runs, which can be the entire connection\nlifetime. For FR_BACKGROUND requests fc-\u003enum_background is never\ndecremented either, so repeated cancels inflate the counter until\nmax_background is hit and all later background ops stall. tw.cancel does\nnot imply a connection abort (e.g. a single io_uring worker thread exits\nwhile the fuse connection stays up), so this cannot be left for\nfuse_abort_conn() to clean up.\n\nEnding the req but still routing the entry through fuse_uring_send()\nis not enough: that leaves a req-less entry on ent_in_userspace, and\nent_list_request_expired() dereferences ent-\u003efuse_req unconditionally\non the head of that list, which would then NULL-deref.\n\nFix the cancel branch to release the entry directly. Remove it from the\nqueue, complete the io_uring cmd, end the fuse_req, free the entry, and\ndrop its queue_refs (waking the teardown waiter if it was the last)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-25T08:49:12.599Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/4f45f276d5b4412eade6f74f2e37f3adba0473ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd"
        }
      ],
      "title": "fuse-uring: end fuse_req on io-uring cancel task work",
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    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64262",
    "datePublished": "2026-07-25T08:49:12.599Z",
    "dateReserved": "2026-07-19T15:36:31.774Z",
    "dateUpdated": "2026-07-25T08:49:12.599Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64262",
      "date": "2026-07-27",
      "epss": "0.00198",
      "percentile": "0.09845"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64262\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-25T10:17:06.350\",\"lastModified\":\"2026-07-25T10:17:06.350\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nfuse-uring: end fuse_req on io-uring cancel task work\\n\\nWhen io_uring delivers task work with tw.cancel set (PF_EXITING,\\nPF_KTHREAD fallback, or percpu_ref_is_dying on the ring context),\\nfuse_uring_send_in_task() takes the cancel branch, assigns\\n-ECANCELED, and falls through to fuse_uring_send(). That path only\\nflips the entry to FRRS_USERSPACE and completes the io_uring cmd;\\nit never discharges the ring entry\u0027s owning reference to the\\nfuse_req that fuse_uring_add_req_to_ring_ent() handed it at\\ndispatch time.\\n\\n    fuse_uring_send_in_task()\\n      tw.cancel == true\\n        err = -ECANCELED\\n      fuse_uring_send(ent, cmd, err, issue_flags)\\n        ent-\u003estate = FRRS_USERSPACE\\n        list_move(\u0026ent-\u003elist, \u0026queue-\u003eent_in_userspace)\\n        ent-\u003ecmd = NULL\\n        io_uring_cmd_done(-ECANCELED)\\n        /* ent-\u003efuse_req still set, req still hashed */\\n\\nThe fuse_req stays linked on fpq-\u003eprocessing[hash] and\\nfuse_request_end() is never invoked. The originating syscall\\nthread blocks in D-state in request_wait_answer() until\\nfuse_abort_conn() runs, which can be the entire connection\\nlifetime. For FR_BACKGROUND requests fc-\u003enum_background is never\\ndecremented either, so repeated cancels inflate the counter until\\nmax_background is hit and all later background ops stall. tw.cancel does\\nnot imply a connection abort (e.g. a single io_uring worker thread exits\\nwhile the fuse connection stays up), so this cannot be left for\\nfuse_abort_conn() to clean up.\\n\\nEnding the req but still routing the entry through fuse_uring_send()\\nis not enough: that leaves a req-less entry on ent_in_userspace, and\\nent_list_request_expired() dereferences ent-\u003efuse_req unconditionally\\non the head of that list, which would then NULL-deref.\\n\\nFix the cancel branch to release the entry directly. Remove it from the\\nqueue, complete the io_uring cmd, end the fuse_req, free the entry, and\\ndrop its queue_refs (waking the teardown waiter if it was the last).\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/fuse/dev_uring.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"c2c9af9a0b13261c36909036057a116f2edb5e1a\",\"lessThan\":\"bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c2c9af9a0b13261c36909036057a116f2edb5e1a\",\"lessThan\":\"4f45f276d5b4412eade6f74f2e37f3adba0473ed\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c2c9af9a0b13261c36909036057a116f2edb5e1a\",\"lessThan\":\"bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/fuse/dev_uring.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.14\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.14\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.39\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.4\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/4f45f276d5b4412eade6f74f2e37f3adba0473ed\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bb476ef8e1027a9d509fbaaf81f5061a07e9e5a7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bea4fe98204b6ce7eb8e29f7bf867dd7619b3ddd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-25T16:47:04Z",
      "cve": "CVE-2026-64262",
      "id": "CVE-2026-64262",
      "initial_release_date": "2026-07-25T16:47:04Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64262",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64262.json",
      "version": "2"
    }
  }
}



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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.

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  • 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.


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