CVE-2026-98990

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Source
https://cve.org/CVERecord?id=CVE-2026-98990
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98990.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-98990
Downstream
Published
2026-10-23T12:20:09Z
Modified
2026-11-01T02:31:05Z
Summary
namespace: check a submount for references right before unmounting it
Details

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.

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98990.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
1064f874abc0d05eeed8993815f584d847b72486
Fixed
cda0c4e502a0f74a191471ce100fb061e5ab35d6
Fixed
3f55f71291e4332983cd63b288d1f2be3c9c08fc
Fixed
361f59e7f3f9a219fb5567bf9abc8482a154a399
Fixed
f6394281834492c6516a405a348b545ae698a331
Fixed
6e4012e571867868b545c91ca9d6095fdb709907
Fixed
d73f04e92c1aab78d96ac6cadb234c8a3a373d22
Fixed
18902a23ef36f83d32bafc58ae2484e6bb4bb8ef
Fixed
32bf92416614a1e3ff3524fc6b780259c7aad3ef
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.1.40
Fixed
4.2
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.4.54
Fixed
4.5
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.9.15
Fixed
4.10
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
4.10.3
Fixed
4.11
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
808e83e5add13152bd4a88346487de68395c136b
Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
6de9d08a9718ee9c12ba6343c50141c2d633e3dc

Affected versions

v4.*
v4.1.40
v4.1.41
v4.1.42
v4.1.43
v4.1.44
v4.1.45
v4.1.46
v4.1.47
v4.1.48
v4.1.49
v4.1.50
v4.1.51
v4.1.52
v4.10.10
v4.10.11
v4.10.12
v4.10.13
v4.10.14
v4.10.15
v4.10.16
v4.10.17
v4.10.3
v4.10.4
v4.10.5
v4.10.6
v4.10.7
v4.10.8
v4.10.9
v4.4.100
v4.4.101
v4.4.102
v4.4.103
v4.4.104
v4.4.105
v4.4.106
v4.4.107
v4.4.108
v4.4.109
v4.4.110
v4.4.111
v4.4.112
v4.4.113
v4.4.114
v4.4.115
v4.4.116
v4.4.117
v4.4.118
v4.4.119
v4.4.120
v4.4.121
v4.4.122
v4.4.123
v4.4.124
v4.4.125
v4.4.126
v4.4.127
v4.4.128
v4.4.129
v4.4.130
v4.4.131
v4.4.132
v4.4.133
v4.4.134
v4.4.135
v4.4.136
v4.4.137
v4.4.138
v4.4.139
v4.4.140
v4.4.141
v4.4.142
v4.4.143
v4.4.144
v4.4.145
v4.4.146
v4.4.147
v4.4.148
v4.4.149
v4.4.150
v4.4.151
v4.4.152
v4.4.153
v4.4.154
v4.4.155
v4.4.156
v4.4.157
v4.4.158
v4.4.159
v4.4.160
v4.4.161
v4.4.162
v4.4.163
v4.4.164
v4.4.165
v4.4.166
v4.4.167
v4.4.168
v4.4.169
v4.4.170
v4.4.171
v4.4.172
v4.4.173
v4.4.174
v4.4.175
v4.4.176
v4.4.177
v4.4.178
v4.4.179
v4.4.180
v4.4.181
v4.4.182
v4.4.183
v4.4.184
v4.4.185
v4.4.186
v4.4.187
v4.4.188
v4.4.189
v4.4.190
v4.4.191
v4.4.192
v4.4.193
v4.4.194
v4.4.195
v4.4.196
v4.4.197
v4.4.198
v4.4.199
v4.4.200
v4.4.201
v4.4.202
v4.4.203
v4.4.204
v4.4.205
v4.4.206
v4.4.207
v4.4.208
v4.4.209
v4.4.210
v4.4.211
v4.4.212
v4.4.213
v4.4.214
v4.4.215
v4.4.216
v4.4.217
v4.4.218
v4.4.219
v4.4.220
v4.4.221
v4.4.222
v4.4.223
v4.4.224
v4.4.225
v4.4.226
v4.4.227
v4.4.228
v4.4.229
v4.4.230
v4.4.231
v4.4.232
v4.4.233
v4.4.234
v4.4.235
v4.4.236
v4.4.237
v4.4.238
v4.4.239
v4.4.240
v4.4.241
v4.4.242
v4.4.243
v4.4.244
v4.4.245
v4.4.246
v4.4.247
v4.4.248
v4.4.249
v4.4.250
v4.4.251
v4.4.252
v4.4.253
v4.4.254
v4.4.255
v4.4.256
v4.4.257
v4.4.258
v4.4.259
v4.4.260
v4.4.261
v4.4.262
v4.4.263
v4.4.264
v4.4.265
v4.4.266
v4.4.267
v4.4.268
v4.4.269
v4.4.270
v4.4.271
v4.4.272
v4.4.273
v4.4.274
v4.4.275
v4.4.276
v4.4.277
v4.4.278
v4.4.279
v4.4.280
v4.4.281
v4.4.282
v4.4.283
v4.4.284
v4.4.285
v4.4.286
v4.4.287
v4.4.288
v4.4.289
v4.4.290
v4.4.291
v4.4.292
v4.4.293
v4.4.294
v4.4.295
v4.4.296
v4.4.297
v4.4.298
v4.4.299
v4.4.300
v4.4.301
v4.4.302
v4.4.54
v4.4.55
v4.4.56
v4.4.57
v4.4.58
v4.4.59
v4.4.60
v4.4.61
v4.4.62
v4.4.63
v4.4.64
v4.4.65
v4.4.66
v4.4.67
v4.4.68
v4.4.69
v4.4.70
v4.4.71
v4.4.72
v4.4.73
v4.4.74
v4.4.75
v4.4.76
v4.4.77
v4.4.78
v4.4.79
v4.4.80
v4.4.81
v4.4.82
v4.4.83
v4.4.84
v4.4.85
v4.4.86
v4.4.87
v4.4.88
v4.4.89
v4.4.90
v4.4.91
v4.4.92
v4.4.93
v4.4.94
v4.4.95
v4.4.96
v4.4.97
v4.4.98
v4.4.99
v4.9.100
v4.9.101
v4.9.102
v4.9.103
v4.9.104
v4.9.105
v4.9.106
v4.9.107
v4.9.108
v4.9.109
v4.9.110
v4.9.111
v4.9.112
v4.9.113
v4.9.114
v4.9.115
v4.9.116
v4.9.117
v4.9.118
v4.9.119
v4.9.120
v4.9.121
v4.9.122
v4.9.123
v4.9.124
v4.9.125
v4.9.126
v4.9.127
v4.9.128
v4.9.129
v4.9.130
v4.9.131
v4.9.132
v4.9.133
v4.9.134
v4.9.135
v4.9.136
v4.9.137
v4.9.138
v4.9.139
v4.9.140
v4.9.141
v4.9.142
v4.9.143
v4.9.144
v4.9.145
v4.9.146
v4.9.147
v4.9.148
v4.9.149
v4.9.15
v4.9.150
v4.9.151
v4.9.152
v4.9.153
v4.9.154
v4.9.155
v4.9.156
v4.9.157
v4.9.158
v4.9.159
v4.9.16
v4.9.160
v4.9.161
v4.9.162
v4.9.163
v4.9.164
v4.9.165
v4.9.166
v4.9.167
v4.9.168
v4.9.169
v4.9.17
v4.9.170
v4.9.171
v4.9.172
v4.9.173
v4.9.174
v4.9.175
v4.9.176
v4.9.177
v4.9.178
v4.9.179
v4.9.18
v4.9.180
v4.9.181
v4.9.182
v4.9.183
v4.9.184
v4.9.185
v4.9.186
v4.9.187
v4.9.188
v4.9.189
v4.9.19
v4.9.190
v4.9.191
v4.9.192
v4.9.193
v4.9.194
v4.9.195
v4.9.196
v4.9.197
v4.9.198
v4.9.199
v4.9.20
v4.9.200
v4.9.201
v4.9.202
v4.9.203
v4.9.204
v4.9.205
v4.9.206
v4.9.207
v4.9.208
v4.9.209
v4.9.21
v4.9.210
v4.9.211
v4.9.212
v4.9.213
v4.9.214
v4.9.215
v4.9.216
v4.9.217
v4.9.218
v4.9.219
v4.9.22
v4.9.220
v4.9.221
v4.9.222
v4.9.223
v4.9.224
v4.9.225
v4.9.226
v4.9.227
v4.9.228
v4.9.229
v4.9.23
v4.9.230
v4.9.231
v4.9.232
v4.9.233
v4.9.234
v4.9.235
v4.9.236
v4.9.237
v4.9.238
v4.9.239
v4.9.24
v4.9.240
v4.9.241
v4.9.242
v4.9.243
v4.9.244
v4.9.245
v4.9.246
v4.9.247
v4.9.248
v4.9.249
v4.9.25
v4.9.250
v4.9.251
v4.9.252
v4.9.253
v4.9.254
v4.9.255
v4.9.256
v4.9.257
v4.9.258
v4.9.259
v4.9.26
v4.9.260
v4.9.261
v4.9.262
v4.9.263
v4.9.264
v4.9.265
v4.9.266
v4.9.267
v4.9.268
v4.9.269
v4.9.27
v4.9.270
v4.9.271
v4.9.272
v4.9.273
v4.9.274
v4.9.275
v4.9.276
v4.9.277
v4.9.278
v4.9.279
v4.9.28
v4.9.280
v4.9.281
v4.9.282
v4.9.283
v4.9.284
v4.9.285
v4.9.286
v4.9.287
v4.9.288
v4.9.289
v4.9.29
v4.9.290
v4.9.291
v4.9.292
v4.9.293
v4.9.294
v4.9.295
v4.9.296
v4.9.297
v4.9.298
v4.9.299
v4.9.30
v4.9.300
v4.9.301
v4.9.302
v4.9.303
v4.9.304
v4.9.305
v4.9.306
v4.9.307
v4.9.308
v4.9.309
v4.9.31
v4.9.310
v4.9.311
v4.9.312
v4.9.313
v4.9.314
v4.9.315
v4.9.316
v4.9.317
v4.9.318
v4.9.319
v4.9.32
v4.9.320
v4.9.321
v4.9.322
v4.9.323
v4.9.324
v4.9.325
v4.9.326
v4.9.327
v4.9.328
v4.9.329
v4.9.33
v4.9.330
v4.9.331
v4.9.332
v4.9.333
v4.9.334
v4.9.335
v4.9.336
v4.9.337
v4.9.34
v4.9.35
v4.9.36
v4.9.37
v4.9.38
v4.9.39
v4.9.40
v4.9.41
v4.9.42
v4.9.43
v4.9.44
v4.9.45
v4.9.46
v4.9.47
v4.9.48
v4.9.49
v4.9.50
v4.9.51
v4.9.52
v4.9.53
v4.9.54
v4.9.55
v4.9.56
v4.9.57
v4.9.58
v4.9.59
v4.9.60
v4.9.61
v4.9.62
v4.9.63
v4.9.64
v4.9.65
v4.9.66
v4.9.67
v4.9.68
v4.9.69
v4.9.70
v4.9.71
v4.9.72
v4.9.73
v4.9.74
v4.9.75
v4.9.76
v4.9.77
v4.9.78
v4.9.79
v4.9.80
v4.9.81
v4.9.82
v4.9.83
v4.9.84
v4.9.85
v4.9.86
v4.9.87
v4.9.88
v4.9.89
v4.9.90
v4.9.91
v4.9.92
v4.9.93
v4.9.94
v4.9.95
v4.9.96
v4.9.97
v4.9.98
v4.9.99

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98990.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
4.11.0
Fixed
5.10.273
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.224
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.191
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.160
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.113
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.18.57
Type
ECOSYSTEM
Events
Introduced
6.19.0
Fixed
7.2.11

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98990.json"