CVE-2026-64053 (GCVE-0-2026-64053)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-10-19 20:28
VLAI
Title
block: don't overwrite bip_vcnt in bio_integrity_copy_user()
Summary
In the Linux kernel, the following vulnerability has been resolved: block: don't overwrite bip_vcnt in bio_integrity_copy_user() bio_integrity_add_page() already sets bip_vcnt to 1 for the bounce segment. Overwriting it with nr_vecs breaks bip_vcnt <= bip_max_vcnt on WRITE (bip_max_vcnt is 1), so the gap-merge checks in block/blk.h read past the bip_vec[] flex array. On READ the read is in bounds but lands on a saved user bvec instead of the bounce. The line was added for split propagation, but bio_integrity_clone() doesn't copy bip_vcnt and BIP_CLONE_FLAGS excludes BIP_COPY_USER.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 15:36 UTC
CWE
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6843 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3991657ae7074c3c497bf095093178bed37ea1b4 , < d18160c9525c63c203656fefd847e94b538cd4a4 (git)
Affected: 3991657ae7074c3c497bf095093178bed37ea1b4 , < 0d48654af4d1390c888389206cc13b51b82c30e6 (git)
Affected: 3991657ae7074c3c497bf095093178bed37ea1b4 , < 066be1439593a381b1a29663becfcfe0c92363e7 (git)
Affected: 3991657ae7074c3c497bf095093178bed37ea1b4 , < 637ad3a56a3b889527d1dacea6fea2a8bd648140 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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                },
                {
                  "lessThan": "637ad3a56a3b889527d1dacea6fea2a8bd648140",
                  "status": "affected",
                  "version": "3991657ae7074c3c497bf095093178bed37ea1b4",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "block/bio-integrity.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "6.11"
                },
                {
                  "lessThan": "6.11",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.12.*",
                  "status": "unaffected",
                  "version": "6.12.92",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.18.*",
                  "status": "unaffected",
                  "version": "6.18.34",
                  "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": "6.12.92",
                      "versionStartIncluding": "6.11",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.18.34",
                      "versionStartIncluding": "6.11",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "7.0.11",
                      "versionStartIncluding": "6.11",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "7.1",
                      "versionStartIncluding": "6.11",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: don\u0027t overwrite bip_vcnt in bio_integrity_copy_user()\n\nbio_integrity_add_page() already sets bip_vcnt to 1 for the bounce\nsegment. Overwriting it with nr_vecs breaks bip_vcnt \u003c= bip_max_vcnt\non WRITE (bip_max_vcnt is 1), so the gap-merge checks in block/blk.h\nread past the bip_vec[] flex array. On READ the read is in bounds\nbut lands on a saved user bvec instead of the bounce.\n\nThe line was added for split propagation, but bio_integrity_clone()\ndoesn\u0027t copy bip_vcnt and BIP_CLONE_FLAGS excludes BIP_COPY_USER."
            }
          ],
          "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 only reachable via local syscalls on an integrity-capable block device\u2014io_uring read/write with PI attributes (`IOCB_HAS_METADATA` \u2192 `bio_integrity_map_iter()`) or NVMe ioctls (`NVME_IOCTL_SUBMIT_IO`/`NVME_IOCTL_IO_CMD` \u2192 `blk_rq_integrity_map_user()`). No network-facing server path (ksmbd, nfsd, nvmet) calls `bio_integrity_copy_user()`.\nAC:L - An attacker fully controls the conditions needed to hit the copy path and trigger the bad index: misaligned or multi-segment integrity user buffers force `copy=true`, multi-page scatter yields `nr_bvecs\u003e1`, and concurrent O_DIRECT integrity writes to the same queue trigger `integrity_req_gap_*_merge()` that dereferences the corrupted `bip_vcnt`.\nPR:L - No kernel capabilities or init-namespace root are required beyond permission to open and perform O_DIRECT I/O on an integrity-enabled block device (`/dev/nvme*`, SCSI DIF disk); io_uring and NVMe ioctls are available to any local user granted device access (e.g., disk group, container volume mounts on storage nodes).\nUI:N - Exploitation is self-initiated by the attacker issuing crafted integrity I/O; no victim interaction such as mounting a filesystem or opening a file is required.\nS:U - Impact is confined to kernel memory safety within the block-integrity path on the host; it does not cross a VM, IOMMU, or sandbox security boundary.\nC:H - On WRITE, `bip_vcnt` is incorrectly set to `nr_vecs` while `bip_max_vcnt` is 1, so `integrity_req_gap_back_merge()`/`integrity_req_gap_front_merge()` in `block/blk.h` index `bip_vec[bip_vcnt-1]` past the single-slot kmalloc flex array, causing an out-of-bounds read of adjacent kernel heap memory that can disclose kernel pointers and other sensitive data.\nI:H - The corrupted `bip_vcnt` breaks integrity metadata bookkeeping during bio/request merging; on READ it causes gap-merge logic to consult saved user bvecs instead of the kernel bounce buffer, and the heap OOB read corrupts kernel memory-safety invariants in ways that can be chained toward further memory corruption or control-flow manipulation.\nA:H - With large `nr_bvecs` (up to `BIO_MAX_VECS`), the out-of-bounds `bip_vec` access can extend far beyond the kmalloc object boundary and provoke a kernel oops/page fault during merge processing; even without full exploitation, the integrity path malfunction can destabilize the I/O stack."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T12:38:43.588Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/d18160c9525c63c203656fefd847e94b538cd4a4"
            },
            {
              "url": "https://git.kernel.org/stable/c/0d48654af4d1390c888389206cc13b51b82c30e6"
            },
            {
              "url": "https://git.kernel.org/stable/c/066be1439593a381b1a29663becfcfe0c92363e7"
            },
            {
              "url": "https://git.kernel.org/stable/c/637ad3a56a3b889527d1dacea6fea2a8bd648140"
            }
          ],
          "title": "block: don\u0027t overwrite bip_vcnt in bio_integrity_copy_user()",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2026-64053",
        "datePublished": "2026-07-19T15:39:35.854Z",
        "dateReserved": "2026-07-19T07:54:57.029Z",
        "dateUpdated": "2026-10-16T15:42:21.153Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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