Vulnerability-Lookup

FKIE_CVE-2025-39939

Vulnerability from fkie_nvd - Published: 2025-10-04 08:15 - Updated: 2026-10-19 21:10

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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: iommu/s390: Fix memory corruption when using identity domain zpci_get_iommu_ctrs() returns counter information to be reported as part of device statistics; these counters are stored as part of the s390_domain. The problem, however, is that the identity domain is not backed by an s390_domain and so the conversion via to_s390_domain() yields a bad address that is zero'd initially and read on-demand later via a sysfs read. These counters aren't necessary for the identity domain; just return NULL in this case. This issue was discovered via KASAN with reports that look like: BUG: KASAN: global-out-of-bounds in zpci_fmb_enable_device when using the identity domain for a device on s390.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/17a58caf3863163c4a84a218a9649be2c8061443	Patch
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b3506e9bcc777ed6af2ab631c86a9990ed97b474	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17
linux	linux_kernel	6.17

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/s390-iommu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "64af12c6ec3afd7d44bc8b2044eee59f98059087",
              "versionType": "git"
            },
            {
              "lessThan": "b3506e9bcc777ed6af2ab631c86a9990ed97b474",
              "status": "affected",
              "version": "64af12c6ec3afd7d44bc8b2044eee59f98059087",
              "versionType": "git"
            }
          ]
        },
        {
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
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              "versionEndExcluding": "6.16.9",
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              "vulnerable": true
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/s390: Fix memory corruption when using identity domain\n\nzpci_get_iommu_ctrs() returns counter information to be reported as part\nof device statistics; these counters are stored as part of the s390_domain.\nThe problem, however, is that the identity domain is not backed by an\ns390_domain and so the conversion via to_s390_domain() yields a bad address\nthat is zero\u0027d initially and read on-demand later via a sysfs read.\nThese counters aren\u0027t necessary for the identity domain; just return NULL\nin this case.\n\nThis issue was discovered via KASAN with reports that look like:\nBUG: KASAN: global-out-of-bounds in zpci_fmb_enable_device\nwhen using the identity domain for a device on s390."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\niommu/s390: Corregir corrupci\u00f3n de memoria al usar el dominio de identidad\n\nzpci_get_iommu_ctrs() devuelve informaci\u00f3n de contador para ser reportada como parte de las estad\u00edsticas del dispositivo; estos contadores se almacenan como parte del s390_domain. El problema, sin embargo, es que el dominio de identidad no est\u00e1 respaldado por un s390_domain y por lo tanto la conversi\u00f3n a trav\u00e9s de to_s390_domain() produce una direcci\u00f3n incorrecta que se pone a cero inicialmente y se lee bajo demanda m\u00e1s tarde a trav\u00e9s de una lectura de sysfs. Estos contadores no son necesarios para el dominio de identidad; simplemente devolver NULL en este caso.\n\nEste problema fue descubierto a trav\u00e9s de KASAN con informes que se ven as\u00ed:\nBUG: KASAN: global-out-of-bounds en zpci_fmb_enable_device\nal usar el dominio de identidad para un dispositivo en s390."
    }
  ],
  "id": "CVE-2025-39939",
  "lastModified": "2026-10-19T21:10:00.160",
  "metrics": {
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          "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",
          "version": "3.1"
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        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      },
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          "availabilityImpact": "HIGH",
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          "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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        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
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    "ssvcV203": [
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        "ssvcData": {
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          "options": [
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            },
            {
              "technicalImpact": "total"
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          "role": "CISA Coordinator",
          "timestamp": "2026-10-15T21:54:54.159629Z",
          "version": "2.0.3"
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  "published": "2025-10-04T08:15:46.860",
  "references": [
    {
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      "tags": [
        "Patch"
      ],
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    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-787"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2025-39939 (GCVE-0-2025-39939)

Vulnerability from cvelistv5 – Published: 2025-10-04 07:31 – Updated: 2026-10-15 22:02

Title

iommu/s390: Fix memory corruption when using identity domain

Summary

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 2026-10-15 21:54 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6820 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/17a58caf3863163c4…
https://git.kernel.org/stable/c/b3506e9bcc777ed6a…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 64af12c6ec3afd7d44bc8b2044eee59f98059087 , < 17a58caf3863163c4a84a218a9649be2c8061443 (git) Affected: 64af12c6ec3afd7d44bc8b2044eee59f98059087 , < b3506e9bcc777ed6af2ab631c86a9990ed97b474 (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.16.9 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-39939",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-15T21:54:54.159629Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/s390-iommu.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
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              "version": "64af12c6ec3afd7d44bc8b2044eee59f98059087",
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              "status": "affected",
              "version": "64af12c6ec3afd7d44bc8b2044eee59f98059087",
              "versionType": "git"
            }
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          "product": "Linux",
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          "versions": [
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              "status": "unaffected",
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              "version": "6.16.9",
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              "value": "AV:L - The vulnerable code is s390 PCI/IOMMU infrastructure reached through local interfaces only \u2014 `pci_enable_device()` on driver bind and the debugfs `/sys/kernel/debug/pci/\u003cdev\u003e/statistics` file. There is no network-facing path to `zpci_get_iommu_ctrs()`.\nAC:L - Once a device uses the identity domain, the out-of-bounds access is fully deterministic \u2014 no race to win and no attacker-uninfluenceable memory layout \u2014 corrupting the same fixed 40-byte region on every `zpci_fmb_enable_device()` call and leaking it on every statistics read. Passthrough mode is a supported, documented runtime option on s390, not an obscure debug-only Kconfig.\nPR:L - The corrupting write happens automatically during normal `pci_enable_device()` at boot/driver bind with no attacker action at all, and the disclosure file is created world-readable (`S_IFREG | S_IRUGO | S_IWUSR`), so an unprivileged local user on a system with a traversable debugfs can harvest the leaked kernel global memory. No capability check gates `zpci_get_iommu_ctrs()` itself.\nUI:N - No victim action is needed; the counter reset fires on device enable and the OOB read happens on a plain file read. Nothing requires a second user to mount, open, or configure anything.\nS:U - The corruption and disclosure are confined to kernel `.data` within the kernel\u0027s own security authority \u2014 the bug mislocates statistics counters and does not alter IOMMU translation or bypass the DMA isolation boundary. Standard kernel-internal memory corruption is Unchanged scope.\nC:H - `pci_sw_counter_show()` reads 40 bytes past the end of `s390_identity_domain` and prints them verbatim to userspace, disclosing adjacent kernel global data such as `blocking_domain`\u0027s `ops`/`owner` function-pointer and structure pointers \u2014 a direct kernel address leak defeating KASLR and exposing kernel state.\nI:H - Five `atomic64_set()` calls zero 40 bytes of adjacent kernel global memory, overwriting live control structures \u2014 at +16 past the object this lands exactly on an `iommu_domain`\u0027s `const struct iommu_domain_ops *ops` field, nulling a function-pointer table. This is genuine kernel memory corruption of security-relevant control data, as the commit subject states.\nA:H - Zeroing adjacent globals (e.g. `blocking_domain.ops`) produces NULL-pointer dereferences in `__iommu_attach_device()` when the blocking/release domain is later attached, and KASAN reports a `global-out-of-bounds` BUG in `zpci_fmb_enable_device`. Both result in a kernel oops/panic."
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    "cveId": "CVE-2025-39939",
    "datePublished": "2025-10-04T07:31:02.521Z",
    "dateReserved": "2025-04-16T07:20:57.148Z",
    "dateUpdated": "2026-10-15T22:02:33.574Z",
    "state": "PUBLISHED"
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}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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