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CVE-2026-72310 (GCVE-0-2026-72310)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:42
VLAI
Title
smb: client: fix overflow in passthrough ioctl bounds check
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix overflow in passthrough ioctl bounds check smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload before copying it to userspace. The payload offset and length both come from 32-bit fields. The bounds check currently adds OutputOffset and qi.input_buffer_length directly, so the addition can wrap in 32-bit arithmetic before the result is compared against the response buffer length. A malicious server can use a large OutputOffset and a small OutputCount to make the wrapped sum pass the bounds check. The later copy_to_user() then reads from io_rsp + OutputOffset, outside the response buffer. Use size_add() for the offset plus length check so overflow is treated as out of bounds.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < 175357ee0c596cb82054650dfa32fda51ad35aaa (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < dbd126539c098dba3159ce7d34b10b2daddcbd0f (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < 63feb687e89a3a52a31e6e01764117cc500f1974 (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < 160045fc943f6c46b227644261252c8a22b8a87a (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < b30771b69eafae750afb7385fbcc3d77ed3f3670 (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < 1627e7d5c9b09721a141d07cedb178882f1ded67 (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < 1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9 (git)
Affected: 2b1116bbe898aefdf584838448c6869f69851e0f , < a4f27ad055392fa164f5649e89a3637b033c5fcc (git)
Affected: 2005c32ec99ee2490e8131b3953f3f212009ffea (git)
Affected: 5.4.69 , < 5.5 (semver)
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Linux Linux Affected: 5.5
Unaffected: 0 , < 5.5 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix overflow in passthrough ioctl bounds check\n\nsmb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload\nbefore copying it to userspace.\n\nThe payload offset and length both come from 32-bit fields. The bounds\ncheck currently adds OutputOffset and qi.input_buffer_length directly, so\nthe addition can wrap in 32-bit arithmetic before the result is compared\nagainst the response buffer length.\n\nA malicious server can use a large OutputOffset and a small OutputCount\nto make the wrapped sum pass the bounds check. The later copy_to_user()\nthen reads from io_rsp + OutputOffset, outside the response buffer.\n\nUse size_add() for the offset plus length check so overflow is treated as\nout of bounds."
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            "version": "3.1"
          },
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              "value": "AV:N - Exploitation requires processing a crafted SMB2 IOCTL response from a malicious SMB/CIFS server over TCP; the bug is in client-side parsing of attacker-controlled network protocol fields, not in a purely local code path.\nAC:L - A malicious server can reliably supply OutputOffset and OutputCount values that wrap the 32-bit bounds check and pass validation, deterministically triggering the out-of-bounds copy_to_user() without races or special victim state.\nPR:L - The PASSTHRU_FSCTL ioctl path requires CAP_SYS_ADMIN, which an unprivileged local user can obtain inside a user namespace and use to mount CIFS and issue CIFS_QUERY_INFO against an attacker-controlled server.\nUI:N - In the highest-impact scenario the attacker controls the full chain (user-namespace mount plus ioctl) and needs no separate victim action beyond their own exploitation steps.\nS:U - Impact is disclosure of kernel heap memory to the calling userspace process within the same kernel security authority; it does not cross VM, IOMMU, or sandbox boundaries.\nC:H - The integer overflow bypasses bounds checking so copy_to_user() reads qi.input_buffer_length bytes from io_rsp plus attacker-chosen OutputOffset outside the SMB response buffer, leaking adjacent kernel memory to userspace.\nI:N - The flaw is an out-of-bounds kernel read copied to userspace; it does not modify kernel memory, corrupt metadata, or provide a write or code-execution primitive.\nA:H - Reading far outside the allocated SMB response buffer can access unmapped kernel pages during copy_to_user(), causing a kernel fault, oops, or panic in addition to information disclosure."
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        "shortName": "Linux"
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    "dateReserved": "2026-08-09T03:40:39.918Z",
    "dateUpdated": "2026-08-17T05:42:38.636Z",
    "state": "PUBLISHED"
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The later copy_to_user()\\nthen reads from io_rsp + OutputOffset, outside the response buffer.\\n\\nUse size_add() for the offset plus length check so overflow is treated as\\nout of bounds.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/smb2ops.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"175357ee0c596cb82054650dfa32fda51ad35aaa\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"dbd126539c098dba3159ce7d34b10b2daddcbd0f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"63feb687e89a3a52a31e6e01764117cc500f1974\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"160045fc943f6c46b227644261252c8a22b8a87a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"b30771b69eafae750afb7385fbcc3d77ed3f3670\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"1627e7d5c9b09721a141d07cedb178882f1ded67\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2b1116bbe898aefdf584838448c6869f69851e0f\",\"lessThan\":\"a4f27ad055392fa164f5649e89a3637b033c5fcc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2005c32ec99ee2490e8131b3953f3f212009ffea\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5.4.69\",\"lessThan\":\"5.5\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/client/smb2ops.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.5\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.5\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.261\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.212\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H\",\"baseScore\":8.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/160045fc943f6c46b227644261252c8a22b8a87a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1627e7d5c9b09721a141d07cedb178882f1ded67\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/175357ee0c596cb82054650dfa32fda51ad35aaa\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/63feb687e89a3a52a31e6e01764117cc500f1974\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a4f27ad055392fa164f5649e89a3637b033c5fcc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b30771b69eafae750afb7385fbcc3d77ed3f3670\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dbd126539c098dba3159ce7d34b10b2daddcbd0f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-17T13:41:00+00:00",
      "cve": "CVE-2026-72310",
      "id": "CVE-2026-72310",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "232",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix overflow in passthrough ioctl bounds check",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72310.json",
      "version": "3"
    }
  }
}



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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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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