{"id":"CVE-2026-68148","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-68148","summary":"fscrypt: Add missing superblock check in find_or_insert_direct_key()","details":"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 'fscrypt_direct_keys' table caches master keys that are used\nby v1 encryption policies that have FSCRYPT_POLICY_FLAG_DIRECT_KEY.\nIt's 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 ('struct fscrypt_direct_key') 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't\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't exist in the v2 policy equivalent\n(\"per-mode keys\"), since the data structures there are per super_block.","published":"2026-08-10T11:59:13.413Z","modified":"2026-08-14T04:03:27.115146720Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.6.148"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/330249609b70778094a7a36f5b6bcfa6362121d4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/466f187b501a5ac8e1ea2ccf3ccd5c46108d8830"},{"type":"WEB","url":"https://git.kernel.org/stable/c/95376fe9c145be35566991df99c53134943d992f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b5fa40226e71c17847b9ff2816c6ca4133d0d994"},{"type":"WEB","url":"https://git.kernel.org/stable/c/deff41898a5ae3a47db5fa1896a494aa95efda5d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68148.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68148"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-14T04:03:27.115146720Z"}}