CVE-2026-90324 (GCVE-0-2026-90324)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:08 – Updated: 2026-09-18 17:54
VLAI
Title
ublk: check import_ubuf() return value
Summary
In the Linux kernel, the following vulnerability has been resolved: ublk: check import_ubuf() return value import_ubuf() can fail if the address range (provided by the userspace ublk server) is outside the allowed user address space. Return that 0 bytes were copied if import_ubuf() fails rather than passing an uninitialized struct iov_iter to ublk_copy_user_pages().
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: 981f95a571e3ca20a496c0b77dbf6b06039c6648 , < 0121c84adb6a4cd6f7560b5895bd88f9899bbc1f (git)
Affected: 981f95a571e3ca20a496c0b77dbf6b06039c6648 , < 5ac6019cb78e98c9608fda72726b36ddf8474dd7 (git)
Affected: 981f95a571e3ca20a496c0b77dbf6b06039c6648 , < 3831568792af75b6523fa93bb91560e29189cf55 (git)
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Linux Linux Affected: 6.5
Unaffected: 0 , < 6.5 (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/ublk_drv.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
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              "version": "981f95a571e3ca20a496c0b77dbf6b06039c6648",
              "versionType": "git"
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              "status": "affected",
              "version": "981f95a571e3ca20a496c0b77dbf6b06039c6648",
              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "version": "6.5"
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              "versionType": "semver"
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              "versionType": "semver"
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              "version": "7.2.6",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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                  "versionStartIncluding": "6.5",
                  "vulnerable": true
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                {
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: check import_ubuf() return value\n\nimport_ubuf() can fail if the address range (provided by the userspace\nublk server) is outside the allowed user address space. Return that 0\nbytes were copied if import_ubuf() fails rather than passing an\nuninitialized struct iov_iter to ublk_copy_user_pages()."
        }
      ],
      "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 bad pointer is io-\u003ebuf.addr from ublksrv_io_cmd.addr in ublk_ch_uring_cmd_local() on UBLK_IO_FETCH_REQ, UBLK_IO_COMMIT_AND_FETCH_REQ, or UBLK_IO_NEED_GET_DATA against /dev/ublkcN. import_ubuf() in ublk_map_io()/ublk_unmap_io() is handed that local userspace address; no network protocol carries it.\nAC:L - The ublk server chooses the FETCH/COMMIT buffer address. A non-zero kernel or wrap-around address fails access_ok() in import_ubuf() on every call (ublk_check_fetch_buf() only rejects addr==0). ublk_map_io()/ublk_unmap_io() then pass the uninitialized iov_iter to ublk_copy_user_pages() with no race or victim state.\nPR:L - ublk_ctrl_add_dev() lets a caller without CAP_SYS_ADMIN create a UBLK_F_UNPRIVILEGED_DEV device, and those devices cannot set UBLK_F_USER_COPY, UBLK_F_SUPPORT_ZERO_COPY, or UBLK_F_AUTO_BUF_REG, so ublk_need_map_io() is always true. ublk_ch_open() has no capability check; ublk_open() allows the owner to issue I/O to /dev/ublkbN.\nUI:N - The attacking process itself issues UBLK_CMD_ADD_DEV and UBLK_CMD_START_DEV on /dev/ublk-control, UBLK_IO_FETCH_REQ with the bad addr on /dev/ublkcN, then read/write on its own ublkb disk so ublk_queue_rq() \u2192 ublk_cmd_tw_cb() \u2192 ublk_dispatch_req() runs. No other user must mount or open anything.\nS:U - ublk_copy_user_pages() copies between the ublk request bio pages and the confused iov_iter entirely inside the host kernel via _copy_to_iter()/_copy_from_iter(). This is local kernel memory corruption, not a VM, IOMMU, or hypervisor escape.\nC:H - On a READ, ublk_unmap_io() calls _copy_from_iter() with the uninitialized iov_iter. iterate_and_advance() may treat leftover iter_type as ITER_KVEC or ITER_BVEC, so memcpy_from_iter() copies kernel memory into the request bio pages, which the attacker then reads from /dev/ublkbN.\nI:H - On a WRITE, ublk_map_io() calls _copy_to_iter() with that uninitialized iter, so iterate_kvec()/memcpy_to_iter() can write the attacker-controlled ublkb write payload to leftover kernel pointers. Garbage iter_type is iov_iter type confusion and an arbitrary kernel write.\nA:H - iterate_kvec() loads p-\u003eiov_len from leftover kvec pointers and iterate_bvec() calls kmap_local_page() on leftover bv_page, either of which oopses. ublk_unmap_io() also hits WARN_ON_ONCE(!data_source) in _copy_from_iter() when the iter was left with data_source==0."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:54:36.580Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/0121c84adb6a4cd6f7560b5895bd88f9899bbc1f"
        },
        {
          "url": "https://git.kernel.org/stable/c/5ac6019cb78e98c9608fda72726b36ddf8474dd7"
        },
        {
          "url": "https://git.kernel.org/stable/c/3831568792af75b6523fa93bb91560e29189cf55"
        }
      ],
      "title": "ublk: check import_ubuf() return value",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90324",
    "datePublished": "2026-09-17T16:08:40.077Z",
    "dateReserved": "2026-09-11T19:38:34.802Z",
    "dateUpdated": "2026-09-18T17:54:36.580Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-25",
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      "percentile": "0.05974"
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                "product": "Linux",
                "programFiles": [
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                ],
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                    "versionType": "semver"
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                    "version": "7.2.6",
                    "versionType": "semver"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: check import_ubuf() return value\n\nimport_ubuf() can fail if the address range (provided by the userspace\nublk server) is outside the allowed user address space. Return that 0\nbytes were copied if import_ubuf() fails rather than passing an\nuninitialized struct iov_iter to ublk_copy_user_pages()."
          }
        ],
        "id": "CVE-2026-90324",
        "lastModified": "2026-09-18T18:17:53.840",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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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.