{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74343", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.886Z", "datePublished": "2026-08-15T05:58:32.577Z", "dateUpdated": "2026-08-17T05:46:08.382Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:46:08.382Z" }, "descriptions": [ { "lang": "en", "value": "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" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only through local VFS xattr operations (setxattr/fsetxattr syscalls) on kernfs-backed mounts such as cgroup2 and sysfs; there is no network-facing handler or remote pre-auth path to the vulnerable code.\nAC:L - The attacker fully controls both racing threads by mounting the same kernfs hierarchy from different namespace-tagged superblocks (e.g. sysfs in two network namespaces) and issuing concurrent setxattr calls against the same shared kernfs_node.\nPR:L - Exploitation requires only local user capabilities obtainable in an unprivileged user namespace (CAP_SYS_ADMIN to create namespaces and mount cgroup2/sysfs), not init-namespace root or host administrator privileges.\nUI:N - No victim interaction is required; the attacker mounts the filesystems, selects the target kernfs_node, and triggers the race with their own concurrent setxattr operations.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel/host security boundary; this is not a VM escape, sandbox breakout, or cross-authority scope change.\nC:H - Concurrent unsynchronized simple_xattr_set() on a shared rhashtable/list can cause use-after-free and heap corruption, which is readily weaponizable for arbitrary kernel memory disclosure, not merely a bounded leak.\nI:H - The race corrupts shared xattr rhashtable and list structures, enabling use-after-free and heap metadata corruption that can be leveraged for arbitrary kernel writes and local privilege escalation/code execution.\nA:H - The race can trigger kernel oops/panic from list/rhashtable corruption or use-after-free during concurrent replace/remove/free paths, causing complete loss of kernel availability even without full exploitation." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/kernfs/file.c", "fs/kernfs/inode.c", "fs/kernfs/kernfs-internal.h", "fs/kernfs/mount.c", "include/linux/kernfs.h" ], "versions": [ { "version": "b32c4a213698ab351b44da2fd1b2a5976c7fa033", "lessThan": "bf53db51359939755084d08156684ed649489592", "status": "affected", "versionType": "git" }, { "version": "b32c4a213698ab351b44da2fd1b2a5976c7fa033", "lessThan": "6a07814ff643b5c8e1353d8c6229f52fde205cde", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/kernfs/file.c", "fs/kernfs/inode.c", "fs/kernfs/kernfs-internal.h", "fs/kernfs/mount.c", "include/linux/kernfs.h" ], "versions": [ { "version": "7.1", "status": "affected" }, { "version": "0", "lessThan": "7.1", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/bf53db51359939755084d08156684ed649489592" }, { "url": "https://git.kernel.org/stable/c/6a07814ff643b5c8e1353d8c6229f52fde205cde" } ], "title": "kernfs: fix xattr race condition with multiple superblocks", "x_generator": { "engine": "bippy-1.2.0" } } } }