CVE-2026-80551 (GCVE-0-2026-80551)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 12:40
VLAI
Title
s390/vfio_ccw: Ensure first IDAW remains constant
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Ensure first IDAW remains constant The first IDAW in a list does not need to be on a 2K/4K boundary like all others, and so is read separately to accurately calculate the size of the buffer needed to read the full IDAL. Verify that the address found in the first IDAW is unchanged between reads, to ensure a consistent set of IDAWs being worked with.
Severity
9.3 (Critical)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 01aa26c672c0eb771de4aaa2a8ccf6055778887b , < 460b977a4e71cc319fdadf91c193ec3beaa57263 (git)
Affected: 01aa26c672c0eb771de4aaa2a8ccf6055778887b , < 0d46c2565f173bcddcdcaf44a4f69789a20535e2 (git)
Affected: 01aa26c672c0eb771de4aaa2a8ccf6055778887b , < 08ef2a82115690d6e229615872ac1731af732497 (git)
Affected: 01aa26c672c0eb771de4aaa2a8ccf6055778887b , < fc59e9482117ebdccd6dc7fa8082f8b980fd021e (git)
Affected: 01aa26c672c0eb771de4aaa2a8ccf6055778887b , < 565bef268d75bf7df665bce6923a88cd0eb74592 (git)
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Linux Linux Affected: 5.3
Unaffected: 0 , < 5.3 (semver)
Unaffected: 6.6.154 , ≤ 6.6.* (semver)
Unaffected: 6.12.105 , ≤ 6.12.* (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/s390/cio/vfio_ccw_cp.c",
            "drivers/s390/cio/vfio_ccw_cp.h"
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          "vendor": "Linux",
          "versions": [
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              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Ensure first IDAW remains constant\n\nThe first IDAW in a list does not need to be on a 2K/4K boundary\nlike all others, and so is read separately to accurately calculate\nthe size of the buffer needed to read the full IDAL.\n\nVerify that the address found in the first IDAW is unchanged between\nreads, to ensure a consistent set of IDAWs being worked with."
        }
      ],
      "metrics": [
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is reached only via local VFIO-ccw mediated-device write()/ioctl on the I/O region (QEMU relaying guest SSCH/channel programs into fsm_io_request\u2192cp_prefetch\u2192ccwchain_fetch_ccw); vfio-ccw has no network, adjacent-radio, or physical-bus entry point.\nAC:L - The malicious guest fully controls guest IDAL memory and can mutate the first IDAW between ccw_count_idaws() and get_guest_idal() using another vCPU and repeated I/O submissions; the attacker controls both sides of this TOCTOU window without uncontrollable host layout or timing luck.\nPR:N - A malicious VM guest with an assigned vfio-ccw mediated subchannel needs no host credentials or capabilities; it only issues guest channel programs with IDA CCWs that QEMU forwards into cp_prefetch(), requiring none of the administrator privileges used to create the mdev.\nUI:N - Exploitation requires only the attacker\u0027s own guest channel program submission through normal passthrough I/O; no separate victim mount, click, or user action is needed once the device is assigned.\nS:C - Guest-supplied IDAL channel programs are parsed and translated in the host kernel during cp_prefetch(), so inconsistent IDAW handling crosses the guest-to-host VFIO device-passthrough boundary and can compromise the hypervisor and co-resident VMs.\nC:H - If the first IDAW changes between reads, idaw_nr can be under-counted and page_array_pin() may omit guest pages while hardware DMA still runs, enabling reads of unpinned host kernel memory and disclosure beyond the guest boundary.\nI:H - Mismatched IDAW sizing lets a guest craft channel programs that pin one set of pages but execute I/O against another, causing host memory corruption via misdirected DMA and supporting further arbitrary-write or control-flow hijack primitives.\nA:H - Inconsistent IDAL translation can immediately fault the host kernel during page pinning or channel I/O completion, and repeated guest-triggered SSCH submissions can reliably panic or hang the hypervisor and all co-hosted VMs."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T12:40:11.187Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/565bef268d75bf7df665bce6923a88cd0eb74592"
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      "title": "s390/vfio_ccw: Ensure first IDAW remains constant",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80551",
    "datePublished": "2026-08-26T14:37:20.554Z",
    "dateReserved": "2026-08-26T14:34:25.766Z",
    "dateUpdated": "2026-08-27T12:40:11.187Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-08-30",
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T14:55:01+00:00",
      "cve": "CVE-2026-80551",
      "id": "CVE-2026-80551",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: s390/vfio_ccw: Ensure first IDAW remains constant",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80551.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

Author Source Type Date Other

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.
  • 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.


Detection rules are retrieved from Rulezet.