{"id":"CVE-2026-74343","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74343","summary":"kernfs: fix xattr race condition with multiple superblocks","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nkernfs: fix xattr race condition with multiple superblocks\n\nMultiple superblocks with different namespaces can share the same\nkernfs_node when kernfs_test_super() finds a matching root but\ndifferent namespace. This means multiple inodes from different\nsuperblocks can reference the same kernfs_node->iattr->xattrs\nstructure.\n\nThe VFS layer only holds per-inode locks during xattr operations,\nwhich is insufficient to serialize concurrent xattr modifications on\nthe shared kernfs_node. This can lead to race conditions in\nsimple_xattr_set() where the lookup->replace/remove sequence is not\natomic with respect to operations from other superblocks.\n\nFix this by protecting xattr operations with the existing hashed\nkernfs_locks->open_file_mutex[] array, which is already used to\nprotect per-node open file data. The hashed mutex array provides\nscalable per-node serialization (scaled by CPU count, up to 1024 locks\non 32+ CPU systems) with zero memory overhead.\n\nChanges:\n- Rename open_file_mutex[] to node_mutex[] to reflect dual purpose\n- Add kernfs_node_lock_ptr() and kernfs_node_lock() helpers\n- Protect simple_xattr_set() calls in kernfs_xattr_set() and\n  kernfs_vfs_user_xattr_set() with the hashed mutex\n- Update file.c to use new helpers via compatibility wrappers\n- Update documentation to explain the extended lock usage","published":"2026-08-15T05:58:32.577Z","modified":"2026-08-18T03:56:56.943918178Z","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":"7.1.5"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/6a07814ff643b5c8e1353d8c6229f52fde205cde"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bf53db51359939755084d08156684ed649489592"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74343.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74343"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-18T03:56:56.943918178Z"}}