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userfaultfd: prevent registration of special VMAs

Type: advisorySource: OSV1 source record

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: prevent registration of special VMAs Vova Tokarev says: userfaultfd allows registration on shadow stack VMAs. With userfaultfd access, you can register on the shadow stack, discard a page ... and inject a page with chosen return addresses via UFFDIO_COPY. Update vma_can_userfault() to reject VM_SHADOW_STACK. While on it, also reject VM_SPECIAL so that if a driver would implement vm_uffd_ops, it wouldn't be possible to register special VMAs with userfaultfd. Since VM_SPECIAL includes VM_DONTEXPAND which is set but hugetlb, exclude hugetlb VMAs from the check for VM_SPECIAL.

Announced Source revision 1
Original source ↗

CVE-2026-68166

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:CVE-2026-68166

Kernel

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
6.6.153

Source reference: /affected/1/ranges

6.12.105

Source reference: /affected/1/ranges

6.18.44

Source reference: /affected/1/ranges

7.1.6

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
        "type": "GIT",
        "events": [
          {
            "introduced": "54007f818206dc27309ca423df4c87dd160a7208"
          },
          {
            "fixed": "d974b4b786214883bd8e56bda10b454c80fd6205"
          },
          {
            "fixed": "495a28d5a100be1b232633f4c2dcc42ba10b3796"
          },
          {
            "fixed": "165613191ad9d034bf17c00e3a142f9561597ec5"
          },
          {
            "fixed": "0c26202b157f1efc3cd2f26f5c30f59b508a6a5d"
          },
          {
            "fixed": "3c58f641e813c3c71039f8fd4d4e2a3aab713288"
          }
        ]
      }
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68166.json"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.6.0"
          },
          {
            "fixed": "6.6.153"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.7.0"
          },
          {
            "fixed": "6.12.105"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.13.0"
          },
          {
            "fixed": "6.18.44"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.19.0"
          },
          {
            "fixed": "7.1.6"
          }
        ]
      }
    ],
    "package": {
      "name": "Kernel",
      "ecosystem": "Linux"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68166.json"
    }
  }
]
Related CVEs
CVE-2026-68166

Source reference: /id

Publisher severity

No explicit severity was provided.

Event
#50761 · Revision 1
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Publisher date
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