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

Vulnerability from cvelistv5 – Published: 2026-08-10 11:59 – Updated: 2026-08-17 05:00
VLAI
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
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 1996639f824ce9468395cdb7bcb8f467fa787e77 (git)
Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 1da310b94504d42001e9c32c43c5dc105b777e5f (git)
Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 9e9a82d00c3d10129fc310a7547b24a679d5d920 (git)
Affected: b9873755a6c8ccfce79094c4dce9efa3ecb1a749 , < 3b231f1e9990f4c21220d0a69733ce2105891ff9 (git)
guessed Create a notification for this product.
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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              "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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        "shortName": "Linux"
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    "datePublished": "2026-08-10T11:59:49.344Z",
    "dateReserved": "2026-07-30T09:28:09.373Z",
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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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      "current_release_date": "2026-08-31T11:17:55+00:00",
      "cve": "CVE-2026-68178",
      "id": "CVE-2026-68178",
      "initial_release_date": "2026-08-10T11:59:49.344000+00:00",
      "product_status:known_affected": "1",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: misc: nsm: pin the module while the device is open",
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      "version": "3"
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      "cve": "CVE-2026-68178",
      "id": "CVE-2026-68178",
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      "source": "SUSE CSAF VEX",
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      "title": "SUSE CVE CVE-2026-68178",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68178.json",
      "version": "2"
    }
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}



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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.

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Nomenclature

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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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