CVE-2026-98984 (GCVE-0-2026-98984)
Vulnerability from cvelistv5
Published
2026-10-23 12:20
Modified
2026-10-30 12:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
dcache: don't put a mountpoint on a dentry that's being removed
rmdir(), unlink() and rename() call dont_mount() on the victim and then
detach_mounts() with the victim's inode locked. do_lock_mount() takes
the inode lock of the mountpoint and checks cant_mount() so a mount
can't show up after detach_mounts().
But attach_recursive_mnt() makes a second mountpoint for the root of the
source mount so that the mounts already located at the destination can
be put on top of it. No inode is locked for that one and d_set_mounted()
only refuses a dentry that is unlinked. Between detach_mounts() and
d_delete() the victim is still hashed:
rmrace: b passed dont_mount() and detach_mounts(), sleeping
T2: move_mount(S, /tmp/plcant/x, BENEATH) = 0 errno 0 ()
T1: rmdir(/tmp/plcant/d/b) = 0 errno 0
109 107 0:61 /d/b//deleted /tmp/plcant/x rw,relatime - tmpfs tmpfs rw
108 109 0:63 / /tmp/plcant/x rw,relatime - tmpfs T rw
A bind mount of the directory that's being removed is moved beneath an
existing mount while the rmdir() is located between the two calls. The
mount ends up on the removed directory and nothing will ever detach it.
Check cant_mount() in d_set_mounted() as well. dont_mount() raises the
flag under d_lock before detach_mounts() runs so either the mountpoint
is set first and detach_mounts() finds the mount or the flag is seen and
the mount is refused.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 1064f874abc0d05eeed8993815f584d847b72486 Version: 5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf Version: 839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7 Version: 808e83e5add13152bd4a88346487de68395c136b Version: 6de9d08a9718ee9c12ba6343c50141c2d633e3dc Version: 4.1.40 ≤ Version: 4.4.54 ≤ Version: 4.9.15 ≤ Version: 4.10.3 ≤ |
||
{
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{
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{
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"cpeApplicability": [
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],
"negate": false,
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndcache: don\u0027t put a mountpoint on a dentry that\u0027s being removed\n\nrmdir(), unlink() and rename() call dont_mount() on the victim and then\ndetach_mounts() with the victim\u0027s inode locked. do_lock_mount() takes\nthe inode lock of the mountpoint and checks cant_mount() so a mount\ncan\u0027t show up after detach_mounts().\n\nBut attach_recursive_mnt() makes a second mountpoint for the root of the\nsource mount so that the mounts already located at the destination can\nbe put on top of it. No inode is locked for that one and d_set_mounted()\nonly refuses a dentry that is unlinked. Between detach_mounts() and\nd_delete() the victim is still hashed:\n\n rmrace: b passed dont_mount() and detach_mounts(), sleeping\n T2: move_mount(S, /tmp/plcant/x, BENEATH) = 0 errno 0 ()\n T1: rmdir(/tmp/plcant/d/b) = 0 errno 0\n 109 107 0:61 /d/b//deleted /tmp/plcant/x rw,relatime - tmpfs tmpfs rw\n 108 109 0:63 / /tmp/plcant/x rw,relatime - tmpfs T rw\n\nA bind mount of the directory that\u0027s being removed is moved beneath an\nexisting mount while the rmdir() is located between the two calls. The\nmount ends up on the removed directory and nothing will ever detach it.\n\nCheck cant_mount() in d_set_mounted() as well. dont_mount() raises the\nflag under d_lock before detach_mounts() runs so either the mountpoint\nis set first and detach_mounts() finds the mount or the flag is seen and\nthe mount is refused."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-30T12:40:42.302Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/25e3ce3e2ebdd8ed3fc19dc1f7e3bc487f9240f3"
},
{
"url": "https://git.kernel.org/stable/c/982d231ad863bb14f7bda4852ab942c0203cec4b"
},
{
"url": "https://git.kernel.org/stable/c/96ca40461d8b91e13061ec4afb59bae6f07a516a"
},
{
"url": "https://git.kernel.org/stable/c/5e6bfd9f249f2c74bb63c0f06ad959da3bee0971"
},
{
"url": "https://git.kernel.org/stable/c/793cb67b0f52d00c67bd0e76bc57455b5c70ebb8"
},
{
"url": "https://git.kernel.org/stable/c/390ddcea2a8aca411b931a8e2863a80ccca8d2b3"
},
{
"url": "https://git.kernel.org/stable/c/30a1625022411a387cce9239408ece9955bc9c58"
},
{
"url": "https://git.kernel.org/stable/c/75f4197f1e11d2eb75c2d6f916a7d4764db621e5"
}
],
"title": "dcache: don\u0027t put a mountpoint on a dentry that\u0027s being removed",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-98984",
"datePublished": "2026-10-23T12:20:02.285Z",
"dateReserved": "2026-09-25T10:25:14.384Z",
"dateUpdated": "2026-10-30T12:40:42.302Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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