159 lines
9.3 KiB
JSON
159 lines
9.3 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-98543",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-25T10:25:14.356Z",
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"datePublished": "2026-10-18T15:18:10.823Z",
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"dateUpdated": "2026-10-24T14:09:20.159Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-24T14:09:20.159Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir\n\nbpf_lsm_has_d_inode_locked() makes the verifier rewrite\nbpf_[set|remove]_dentry_xattr() to the _locked variants, which assume\nthat the caller already holds the inode's i_rwsem. The path_unlink and\npath_rmdir hooks are listed, but security_path_unlink() and\nsecurity_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the\nvictim inode's i_rwsem, so a sleepable BPF LSM program attached to\neither hook mutates the victim's xattrs without the lock held.\n\nDrop the two path hooks from d_inode_locked_hooks so that the verifier\nkeeps the locking bpf_[set|remove]_dentry_xattr() variants, which take\nthe lock themselves."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H",
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"baseScore": 7.3,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - unlink(2)/unlinkat(2)/rmdir(2) reach filename_unlinkat()/filename_rmdir() -> security_path_unlink()/security_path_rmdir() -> bpf_lsm_path_*(); vulnerable bpf_lsm_has_d_inode_locked() classification makes the verifier redirect bpf_[set|remove]_dentry_xattr() to _locked functions. The trigger enters locally, not via a protocol.\nAC:L - On UBIFS, one invocation deterministically fails ubifs_xattr_set()/ubifs_xattr_remove()'s inode_is_locked() assertion; for races, the attacker can unlink two hardlinks in different parents concurrently, so separate parent locks do not serialize the same victim. No condition is outside the attacker's control.\nPR:L - bpf_prog_load() gates BPF_PROG_TYPE_LSM on bpf_token_capable(CAP_BPF) and CAP_PERFMON. A delegated bpffs token makes those ns_capable(token->userns, ...) checks, so a namespace-confined non-admin can load and attach the sleepable path hook; without delegation, init-namespace capabilities are required.\nUI:N - The attacker loads and attaches the BPF LSM program, then invokes unlinkat(2) or rmdir(2) on an object it can modify; no victim must mount media, open a file, or perform another action.\nS:C - With bpffs token delegation, a task confined to the token's user namespace can run the faulty BPF LSM program in the host kernel and force a shared host UBIFS read-only, crossing the container or sandbox availability boundary.\nC:N - Neither affected helper returns filesystem or kernel data: bpf_set_dentry_xattr_locked() only passes a verifier-bounded dynptr to __vfs_setxattr(), and the remove helper has no output. The missing i_rwsem is a mutation-ordering flaw, with no demonstrated OOB read, UAF, or disclosure path.\nI:L - btrfs_setxattr() explicitly relies on the inode lock to exclude a concurrent delete between its XATTR_REPLACE lookup and insert; this bug removes that exclusion, so concurrent path_unlink hooks can recreate or lose security.bpf.* metadata. Btrfs tree locking shows no arbitrary-memory-write primitive, limiting integrity impact.\nA:H - ubifs_xattr_set(..., check_lock=true) and ubifs_xattr_remove() assert inode_is_locked(); default ASSACT_RO calls ubifs_ro_mode(), sets SB_RDONLY, and denies later writes. One path hook calling the mis-selected _locked helper can therefore make a mounted UBIFS lose write availability."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/bpf_fs_kfuncs.c"
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],
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"versions": [
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{
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"version": "56467292794b800164df20c076c409ac548e56ec",
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"lessThan": "7504b677c4370c9e4b153c553ff8831c093b1ff6",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "56467292794b800164df20c076c409ac548e56ec",
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"lessThan": "640d37fbd34d03af727dbc567f48c0203d1de6b4",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "56467292794b800164df20c076c409ac548e56ec",
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"lessThan": "35d442ed1f86465e49df3119fb898f985186db13",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/bpf_fs_kfuncs.c"
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],
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"versions": [
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{
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"version": "6.15",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.15",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.55",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.9",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "6.18.55"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "7.2.9"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "7.3"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/7504b677c4370c9e4b153c553ff8831c093b1ff6"
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},
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{
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"url": "https://git.kernel.org/stable/c/640d37fbd34d03af727dbc567f48c0203d1de6b4"
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},
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{
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"url": "https://git.kernel.org/stable/c/35d442ed1f86465e49df3119fb898f985186db13"
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}
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],
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"title": "bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir",
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"x_generator": {
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"engine": "bippy-1.2.0"
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} |