CVE-2026-64017 (GCVE-0-2026-64017)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-19 16:28
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: blk-mq: pop cached request if it is usable When submitting a bio to blk-mq, if the task should sleep after peeking a cached request, but before it pops it, the plug flushes and calls blk_mq_free_plug_rqs, freeing the cached_rqs. This creates a use-after-free bug. Fix this by popping the cached request before any possible blocking calls if it is suitable for use. Popping this request first holds a queue reference, so avoid any serialization races with queue freezes and can safely proceed with dispatching that request to the driver. This potentially increases a timing window from when a driver wants to freeze its queue to when requests stop being dispatched. That scenario is off the fast path though, and drivers need to appropriately handle requests during a freeze request anyway. The downside is the popped element needs to be individually freed when we performed a bio plug merge. The cached request would have had to be freed later anyway, but this patch does it inline with building the plug list instead of after flushing it.
References
Impacted products
Vendor Product Version
Linux Linux Version: b0077e269f6c152e807fdac90b58caf012cdbaab
Version: b0077e269f6c152e807fdac90b58caf012cdbaab
Version: b0077e269f6c152e807fdac90b58caf012cdbaab
Version: b0077e269f6c152e807fdac90b58caf012cdbaab
Version: b5c8e0ff76d10f6bf70a7237678f27c20cf59bc9
Version: e9c309ded295b7f8849097d71ae231456ca79f78
Version: b80056bd75a16e4550873ecefe12bc8fd190b1cf
Version: 33cf52b6e53a6aa55883aa7fb9ceffceff8488a6
Version: 8b6075046470c8756242dfe3fd058813636f69a3
Version: 6.1.72   ≤
Version: 6.5.13   ≤
Version: 6.6.3   ≤
Version: 6.1.75   ≤
Version: 6.6.14   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "block/blk-mq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "23d8ea1e303b5f32d883757a4a707e791dbc9808",
              "status": "affected",
              "version": "b0077e269f6c152e807fdac90b58caf012cdbaab",
              "versionType": "git"
            },
            {
              "lessThan": "97e2d08de282ef76f84ab4ccd00f1acb3f5f999e",
              "status": "affected",
              "version": "b0077e269f6c152e807fdac90b58caf012cdbaab",
              "versionType": "git"
            },
            {
              "lessThan": "388468f7e7d1eab092cf2a39fdfb502e52019ec6",
              "status": "affected",
              "version": "b0077e269f6c152e807fdac90b58caf012cdbaab",
              "versionType": "git"
            },
            {
              "lessThan": "dc278e9bf2b9513a763353e6b9cc21e0f532954e",
              "status": "affected",
              "version": "b0077e269f6c152e807fdac90b58caf012cdbaab",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b5c8e0ff76d10f6bf70a7237678f27c20cf59bc9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e9c309ded295b7f8849097d71ae231456ca79f78",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b80056bd75a16e4550873ecefe12bc8fd190b1cf",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "33cf52b6e53a6aa55883aa7fb9ceffceff8488a6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8b6075046470c8756242dfe3fd058813636f69a3",
              "versionType": "git"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.72",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6",
              "status": "affected",
              "version": "6.5.13",
              "versionType": "semver"
            },
            {
              "lessThan": "6.7",
              "status": "affected",
              "version": "6.6.3",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.75",
              "versionType": "semver"
            },
            {
              "lessThan": "6.7",
              "status": "affected",
              "version": "6.6.14",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "block/blk-mq.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": "6.12.104",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.104",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.45",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.1.72",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.1.75",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-mq: pop cached request if it is usable\n\nWhen submitting a bio to blk-mq, if the task should sleep after peeking\na cached request, but before it pops it, the plug flushes and calls\nblk_mq_free_plug_rqs, freeing the cached_rqs. This creates a\nuse-after-free bug. Fix this by popping the cached request before any\npossible blocking calls if it is suitable for use.\n\nPopping this request first holds a queue reference, so avoid any\nserialization races with queue freezes and can safely proceed with\ndispatching that request to the driver. This potentially increases a\ntiming window from when a driver wants to freeze its queue to when\nrequests stop being dispatched. That scenario is off the fast path\nthough, and drivers need to appropriately handle requests during a\nfreeze request anyway.\n\nThe downside is the popped element needs to be individually freed when\nwe performed a bio plug merge. The cached request would have had to be\nfreed later anyway, but this patch does it inline with building the plug\nlist instead of after flushing it."
        }
      ],
      "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 in `blk_mq_submit_bio()`, reached from local block I/O submission (`submit_bio` via read/write, filesystem I/O, or io_uring). Reliable exploitation requires a `blk_plug` with populated `cached_rqs`, which occurs when io_uring submits batches of 3+ plugged read/write operations (`blk_start_plug_nr_ios`); remote-only paths like nfsd/ksmbd/nvmet typically use `blk_start_plug()` with `nr_ios=1` and do not populate the cached-request list needed to hit the peek-without-pop window.\nAC:L - An attacker controls both sides of the race by batching io_uring I/O and inducing a sleep between peek and pop (e.g., memory pressure during bio split/allocation, or `bio_integrity_prep()` blocking on PI-capable enterprise/cloud NVMe). Plug flush on any schedule is deterministic kernel behavior, not an uncontrollable environmental condition.\nPR:L - Triggering requires only an unprivileged local process able to perform block-backed I/O (normal file read/write or io_uring readv/writev to accessible storage); no root, `CAP_SYS_ADMIN`, or special kernel capabilities are needed beyond standard filesystem/device access available to any local user.\nUI:N - Exploitation is driven entirely by the attacker\u0027s own I/O submissions through io_uring or direct block I/O; no action by another user or administrator is required.\nS:U - Impact is confined to kernel memory via a block-layer use-after-free on `struct request`; this is standard kernel privilege escalation territory and does not cross a VM, IOMMU, or sandbox security boundary.\nC:H - This is a use-after-free of a `struct request` object; the attacker can influence post-free heap contents and dereference freed fields (`rq-\u003eq`, `rq-\u003emq_hctx`, `rq-\u003ebio`), enabling arbitrary kernel memory read primitives.\nI:H - UAF on `struct request` permits controlled writes through subsequent use of the dangling object (`rq-\u003ecmd_flags`, `queuelist`, bio attachment in `blk_mq_bio_to_request`), enabling heap corruption and potential arbitrary code execution in kernel context.\nA:H - The freed request is dereferenced during `blk_mq_use_cached_rq()` and subsequent request setup, causing kernel oops/panic; even without full exploitation, UAF reliably threatens system availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-19T16:28:11.145Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/23d8ea1e303b5f32d883757a4a707e791dbc9808"
        },
        {
          "url": "https://git.kernel.org/stable/c/97e2d08de282ef76f84ab4ccd00f1acb3f5f999e"
        },
        {
          "url": "https://git.kernel.org/stable/c/388468f7e7d1eab092cf2a39fdfb502e52019ec6"
        },
        {
          "url": "https://git.kernel.org/stable/c/dc278e9bf2b9513a763353e6b9cc21e0f532954e"
        }
      ],
      "title": "blk-mq: pop cached request if it is usable",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64017",
    "datePublished": "2026-07-19T15:39:11.989Z",
    "dateReserved": "2026-07-19T07:54:57.027Z",
    "dateUpdated": "2026-08-19T16:28:11.145Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.