Vulnerability-Lookup

GHSA-785R-497W-84XV

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-14 00:31

Details

In the Linux kernel, the following vulnerability has been resolved:

misc: nsm: pin the module while the device is open

misc_open() installs a misc driver's file operations with fops_get(), which pins file_operations::owner before replacing the file's f_op. The NSM misc device leaves nsm_dev_fops.owner unset, so opening /dev/nsm does not take a module reference on the nsm driver.

If the driver is built as a module, an open file descriptor can therefore survive rmmod of the module that provides its ioctl callbacks. A later ioctl through that descriptor can call into unloaded module text.

Set nsm_dev_fops.owner to THIS_MODULE so the misc core holds the module while any /dev/nsm file descriptor is open, matching the lifetime expectation for the installed file operations.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68178"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:04Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: nsm: pin the module while the device is open\n\nmisc_open() installs a misc driver\u0027s file operations with fops_get(),\nwhich pins file_operations::owner before replacing the file\u0027s f_op.  The\nNSM misc device leaves nsm_dev_fops.owner unset, so opening /dev/nsm does\nnot take a module reference on the nsm driver.\n\nIf the driver is built as a module, an open file descriptor can therefore\nsurvive rmmod of the module that provides its ioctl callbacks.  A later\nioctl through that descriptor can call into unloaded module text.\n\nSet nsm_dev_fops.owner to THIS_MODULE so the misc core holds the module\nwhile any /dev/nsm file descriptor is open, matching the lifetime\nexpectation for the installed file operations.",
  "id": "GHSA-785r-497w-84xv",
  "modified": "2026-08-14T00:31:52Z",
  "published": "2026-08-10T15:33:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68178"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1996639f824ce9468395cdb7bcb8f467fa787e77"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1da310b94504d42001e9c32c43c5dc105b777e5f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3b231f1e9990f4c21220d0a69733ce2105891ff9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e9a82d00c3d10129fc310a7547b24a679d5d920"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-68178 (GCVE-0-2026-68178)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-17 05:00

Title

misc: nsm: pin the module while the device is open

Summary

In the Linux kernel, the following vulnerability has been resolved: misc: nsm: pin the module while the device is open misc_open() installs a misc driver's file operations with fops_get(), which pins file_operations::owner before replacing the file's f_op. The NSM misc device leaves nsm_dev_fops.owner unset, so opening /dev/nsm does not take a module reference on the nsm driver. If the driver is built as a module, an open file descriptor can therefore survive rmmod of the module that provides its ioctl callbacks. A later ioctl through that descriptor can call into unloaded module text. Set nsm_dev_fops.owner to THIS_MODULE so the misc core holds the module while any /dev/nsm file descriptor is open, matching the lifetime expectation for the installed file operations.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/1996639f824ce9468…
https://git.kernel.org/stable/c/1da310b94504d4200…
https://git.kernel.org/stable/c/9e9a82d00c3d10129…
https://git.kernel.org/stable/c/3b231f1e9990f4c21…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 1996639f824ce9468395cdb7bcb8f467fa787e77 (git) Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 1da310b94504d42001e9c32c43c5dc105b777e5f (git) Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 9e9a82d00c3d10129fc310a7547b24a679d5d920 (git) Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 3b231f1e9990f4c21220d0a69733ce2105891ff9 (git)
Linux	Linux	Affected: 6.8 Unaffected: 0 , < 6.8 (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/misc/nsm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "1996639f824ce9468395cdb7bcb8f467fa787e77",
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              "versionType": "git"
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              "version": "b9873755a6c8ccfce79094c4dce9efa3ecb1a749",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
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              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "versionType": "semver"
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              "version": "7.1.6",
              "versionType": "semver"
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.8",
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                },
                {
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: nsm: pin the module while the device is open\n\nmisc_open() installs a misc driver\u0027s file operations with fops_get(),\nwhich pins file_operations::owner before replacing the file\u0027s f_op.  The\nNSM misc device leaves nsm_dev_fops.owner unset, so opening /dev/nsm does\nnot take a module reference on the nsm driver.\n\nIf the driver is built as a module, an open file descriptor can therefore\nsurvive rmmod of the module that provides its ioctl callbacks.  A later\nioctl through that descriptor can call into unloaded module text.\n\nSet nsm_dev_fops.owner to THIS_MODULE so the misc core holds the module\nwhile any /dev/nsm file descriptor is open, matching the lifetime\nexpectation for the installed file operations."
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              "lang": "en",
              "value": "AV:L - The bug is reached only via local open()/ioctl syscalls on /dev/nsm (misc_open through vfs_ioctl to nsm_dev_ioctl); the Nitro Secure Module virtio driver has no network, adjacent-wireless, or physical attack surface.\nAC:L - When CONFIG_NSM=m the attacker controls the full sequence: open /dev/nsm to install fops, delete_module(\"nsm\") while fops_get(NULL) leaves the module unpinned, then ioctl on the stale fd to call unloaded text without races or external timing.\nPR:L - /dev/nsm is registered mode 0666 with no capable() checks in nsm_dev_ioctl, so any local process can open and ioctl; unloading the module needs CAP_SYS_MODULE, treated as low-privilege local capability per similar module-lifetime UAF scoring on permissive/user-namespace kernels.\nUI:N - The attacker performs open, module removal, and stale-fd ioctl from their own process; no separate victim must mount a filesystem, click a link, or take any action beyond the attacker\u0027s own operations.\nS:U - The use-after-free corrupts guest kernel memory and executes in kernel context within the Nitro Enclave; impact does not cross hypervisor, parent-instance, VM, or IOMMU security boundaries.\nC:H - Stale ioctl calls into freed module text and file_to_nsm() dereferences freed devm nsm state, exposing reclaimed kernel/module memory and adjacent virtio message buffers through the UAF window.\nI:H - Dispatching nsm_dev_ioctl through freed vmalloc module text is a kernel use-after-free that can be shaped with heap spraying to hijack control flow and achieve arbitrary kernel code execution.\nA:H - Executing code from an unloaded module or dereferencing freed nsm/virtqueue state on ioctl reliably causes kernel oops or panic, and the attacker can repeat the stale-fd ioctl to deny service."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-08-17T05:00:19.564Z",
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        {
          "url": "https://git.kernel.org/stable/c/3b231f1e9990f4c21220d0a69733ce2105891ff9"
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      "title": "misc: nsm: pin the module while the device is open",
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    "cveId": "CVE-2026-68178",
    "datePublished": "2026-08-10T11:59:49.344Z",
    "dateReserved": "2026-07-30T09:28:09.373Z",
    "dateUpdated": "2026-08-17T05:00:19.564Z",
    "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.

Detection rules are retrieved from Rulezet.

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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GHSA-785R-497W-84XV

CVE-2026-68178 (GCVE-0-2026-68178)

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Sightings

Nomenclature