FKIE_CVE-2026-68148

Vulnerability from fkie_nvd - Published: 2026-08-10 13:20 - Updated: 2026-08-19 17:20
Severity
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: fscrypt: Add missing superblock check in find_or_insert_direct_key() The legacy 'fscrypt_direct_keys' table caches master keys that are used by v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY. It's just a global table for all filesystems (since the keys can be provided by the legacy process-subscribed keyrings mechanism, which makes it difficult to reuse super_block::s_master_keys). The entries in it ('struct fscrypt_direct_key') do contain a super_block pointer, though, for passing to fscrypt_destroy_inline_crypt_key() when the last inode that references the key is evicted. However, when finding the fscrypt_direct_key for an inode, we weren't actually comparing the super_block pointer. As a result, inodes with different super_blocks could point to the same fscrypt_direct_key. That could extend the lifetime of a fscrypt_direct_key beyond the super_block it points to, causing a use-after-free later. Fix this by creating distinct fscrypt_direct_key structs for distinct super_block structs. Note that this problem doesn't exist in the v2 policy equivalent ("per-mode keys"), since the data structures there are per super_block.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/965b5bc8cf5031225e057979ce660fec2bd5fbfc
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/crypto/keysetup_v1.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "965b5bc8cf5031225e057979ce660fec2bd5fbfc",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            },
            {
              "lessThan": "330249609b70778094a7a36f5b6bcfa6362121d4",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            },
            {
              "lessThan": "deff41898a5ae3a47db5fa1896a494aa95efda5d",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            },
            {
              "lessThan": "95376fe9c145be35566991df99c53134943d992f",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            },
            {
              "lessThan": "466f187b501a5ac8e1ea2ccf3ccd5c46108d8830",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            },
            {
              "lessThan": "b5fa40226e71c17847b9ff2816c6ca4133d0d994",
              "status": "affected",
              "version": "22e9947a4b2ba255888541bd0111cf00b9b16586",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/crypto/keysetup_v1.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.1"
            },
            {
              "lessThan": "6.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfscrypt: Add missing superblock check in find_or_insert_direct_key()\n\nThe legacy \u0027fscrypt_direct_keys\u0027 table caches master keys that are used\nby v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY.\nIt\u0027s just a global table for all filesystems (since the keys can be\nprovided by the legacy process-subscribed keyrings mechanism, which\nmakes it difficult to reuse super_block::s_master_keys).\n\nThe entries in it (\u0027struct fscrypt_direct_key\u0027) do contain a super_block\npointer, though, for passing to fscrypt_destroy_inline_crypt_key() when\nthe last inode that references the key is evicted.\n\nHowever, when finding the fscrypt_direct_key for an inode, we weren\u0027t\nactually comparing the super_block pointer.  As a result, inodes with\ndifferent super_blocks could point to the same fscrypt_direct_key.  That\ncould extend the lifetime of a fscrypt_direct_key beyond the\nsuper_block it points to, causing a use-after-free later.\n\nFix this by creating distinct fscrypt_direct_key structs for distinct\nsuper_block structs.\n\nNote that this problem doesn\u0027t exist in the v2 policy equivalent\n(\"per-mode keys\"), since the data structures there are per super_block."
    }
  ],
  "id": "CVE-2026-68148",
  "lastModified": "2026-08-19T17:20:32.097",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "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"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-10T13:20:00.737",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/965b5bc8cf5031225e057979ce660fec2bd5fbfc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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