CVE-2026-98990
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the second one propagates into. propagate_umount() moves a surviving overmount off a copy it unmounts and mounts it where the copy was mounted. If that's where the propagated copy of the second victim is looked up the overmount becomes a candidate of the second umount_tree(). It's childless and so trim_one() commits it without looking at its reference count. So a synchronous umount pulls out a busy mount that is in use somewhere else and marks it MNT_SYNC_UMOUNT while it has users: umount2(/tmp/plshrink/p1, 0) = 0 errno 0 cwd is (unreachable) The same two umounts requested one after the other fail with EBUSY. This needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of NFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts inherit the flag. Check each mount right before it is unmounted under the same hold of namespace_sem and mount_lock as the umount itself. Make sure that the algorithm stays linear.
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-10-23 13:17:20.980000
Last modified
2026-10-30 13:21:34.437000
View original CVE JSON
{
"id": "CVE-2026-98990",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-23T13:17:20.980",
"lastModified": "2026-10-30T13:21:34.437",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: check a submount for references right before unmounting it\n\nshrink_submounts() and mark_mounts_for_expiry() first collect all the\nmounts they are allowed to unmount and then unmount them.\n\nWhether a mount is busy is decided by propagate_mount_busy() on the\ntree. But unmounting the first mount changes the tree that the second\none propagates into. propagate_umount()\nmoves a surviving overmount off a copy it unmounts and mounts it where\nthe copy was mounted. If that's where the propagated copy of the second\nvictim is looked up the overmount becomes a candidate of the second\numount_tree(). It's childless and so trim_one() commits it without\nlooking at its reference count.\n\nSo a synchronous umount pulls out a busy mount that is in use somewhere\nelse and marks it MNT_SYNC_UMOUNT while it has users:\n\n umount2(/tmp/plshrink/p1, 0) = 0 errno 0\n cwd is (unreachable)\n\nThe same two umounts requested one after the other fail with EBUSY.\nThis needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of\nNFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts\ninherit the flag.\n\nCheck each mount right before it is unmounted under the same hold of\nnamespace_sem and mount_lock as the umount itself. Make sure that the\nalgorithm stays linear."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/namespace.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
"lessThan": "cda0c4e502a0f74a191471ce100fb061e5ab35d6",
"versionType": "git",
"status": "affected"
},
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
"lessThan": "3f55f71291e4332983cd63b288d1f2be3c9c08fc",
"versionType": "git",
"status": "affected"
},
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
"lessThan": "361f59e7f3f9a219fb5567bf9abc8482a154a399",
"versionType": "git",
"status": "affected"
},
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
"lessThan": "f6394281834492c6516a405a348b545ae698a331",
"versionType": "git",
"status": "affected"
},
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
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"versionType": "git",
"status": "affected"
},
{
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"lessThan": "d73f04e92c1aab78d96ac6cadb234c8a3a373d22",
"versionType": "git",
"status": "affected"
},
{
"version": "1064f874abc0d05eeed8993815f584d847b72486",
"lessThan": "18902a23ef36f83d32bafc58ae2484e6bb4bb8ef",
"versionType": "git",
"status": "affected"
},
{
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"status": "affected"
},
{
"version": "5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf",
"versionType": "git",
"status": "affected"
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{
"version": "839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7",
"versionType": "git",
"status": "affected"
},
{
"version": "808e83e5add13152bd4a88346487de68395c136b",
"versionType": "git",
"status": "affected"
},
{
"version": "6de9d08a9718ee9c12ba6343c50141c2d633e3dc",
"versionType": "git",
"status": "affected"
},
{
"version": "4.1.40",
"lessThan": "4.2",
"versionType": "semver",
"status": "affected"
},
{
"version": "4.4.54",
"lessThan": "4.5",
"versionType": "semver",
"status": "affected"
},
{
"version": "4.9.15",
"lessThan": "4.10",
"versionType": "semver",
"status": "affected"
},
{
"version": "4.10.3",
"lessThan": "4.11",
"versionType": "semver",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"fs/namespace.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "4.11",
"status": "affected"
},
{
"version": "0",
"lessThan": "4.11",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.273",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.224",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.113",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.57",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.11",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/18902a23ef36f83d32bafc58ae2484e6bb4bb8ef",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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{
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"url": "https://git.kernel.org/stable/c/3f55f71291e4332983cd63b288d1f2be3c9c08fc",
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{
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/d73f04e92c1aab78d96ac6cadb234c8a3a373d22",
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{
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}
]
}