CVE-2026-74656
- Source
- https://cve.org/CVERecord?id=CVE-2026-74656
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74656.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-74656
- Downstream
AZL (1)
BELL (1)
DEBIAN (1)
OESA (2)
- Published
- 2026-08-22T15:32:30Z
- Modified
- 2026-10-08T02:51:55Z
- Severity
-
- 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
- Summary
- ipv4: fix use-after-free in fib_nhc_update_mtu()
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
ipv4: fix use-after-free in fib_nhc_update_mtu()
fib_nhc_update_mtu() walks the nexthop exception table under RTNL, but RTNL does not serialize this walk with PMTU exception updates. The walk uses rcu_dereference_protected() with a constant true condition without holding fnhe_lock.
The following interleaving can therefore occur:
CPU 0 CPU 1 fib_nhc_update_mtu() update_or_create_fnhe() load fnhe spin_lock_bh(&fnhe_lock) fnhe_remove_oldest() unlink fnhe kfree_rcu(fnhe, rcu) access fnhe after grace period
KASAN reported:
BUG: KASAN: slab-use-after-free in fib_nhc_update_mtu+0x3df/0x410 Read of size 8 at addr ffff888107d49000 by task poc/90 Call Trace: fib_nhc_update_mtu+0x3df/0x410 fib_sync_mtu+0x7a/0xd0 fib_netdev_event+0x229/0x3f0 netif_set_mtu_ext+0x33a/0x570 dev_set_mtu+0x88/0x120
The same walk updates fnhe_pmtu and fnhe_mtu_locked. These fields form a pair and other writers serialize them with fnhe_lock. RCU alone prevents reclamation, but would still allow concurrent writers to leave a mixed pair.
Walk the table under RCU and acquire fnhe_lock only while updating each exception. RCU keeps the current entry alive while the short critical section serializes its paired PMTU fields. This avoids holding the global lock while scanning all 2048 buckets for every nexthop.
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74656.json" }- References
-
- https://git.kernel.org/stable/c/5a28a4b22dde92f9d293b94236314b8d6181dc4a
- https://git.kernel.org/stable/c/63996ffc594d128ccec8fc0983f91effd2d3adc4
- https://git.kernel.org/stable/c/bc5bde9ce3cc36502839dfe98e068f7303a50982
- https://git.kernel.org/stable/c/dfe388da13aa784851e5ebbea90afbb099075761
- https://git.kernel.org/stable/c/e00f7d2b5f2540a3415a229c982af7a25ff6362e
- https://git.kernel.org/stable/c/e1e602d6b22d5cb1641c4459c487eb18bf569e0a
- https://git.kernel.org/stable/c/ed503eaad62f20cdd5122d7c3078a648a99c8f16
- https://git.kernel.org/stable/c/fd39e711866498ae94fcf9acf6f422a4f045b681
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74656.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-74656
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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
-
Introducedaf7d6cce53694a88d6a1bb60c9a239a6a5144459Fixedfd39e711866498ae94fcf9acf6f422a4f045b681Fixede1e602d6b22d5cb1641c4459c487eb18bf569e0aFixede00f7d2b5f2540a3415a229c982af7a25ff6362eFixeddfe388da13aa784851e5ebbea90afbb099075761Fixed5a28a4b22dde92f9d293b94236314b8d6181dc4aFixed63996ffc594d128ccec8fc0983f91effd2d3adc4Fixeded503eaad62f20cdd5122d7c3078a648a99c8f16Fixedbc5bde9ce3cc36502839dfe98e068f7303a50982
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced3.16.62Fixed3.17
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.4.162Fixed4.5
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.9.134Fixed4.10
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.14.77Fixed4.15
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4.18.15Fixed4.19
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introducedb427832009b97a3ee412ef643a80b15372a7754d
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced2b7e4c735933be79882aba2bed9afa789e03c62f
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced8d59c3a6376bbc6dd3f7303968a719ffba75a4f1
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced9b4869cf385aa16f89c0f019eed4ec4e36aa441c
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introducedff34695ced21e2dfa04d0fa1c5f6c35011fa8117
Affected versions
v3.*
v3.16.62
v3.16.63
v3.16.64
v3.16.65
v3.16.66
v3.16.67
v3.16.68
v3.16.69
v3.16.70
v3.16.71
v3.16.72
v3.16.73
v3.16.74
v3.16.75
v3.16.76
v3.16.77
v3.16.78
v3.16.79
v3.16.80
v3.16.81
v3.16.82
v3.16.83
v3.16.84
v3.16.85
v4.*
v4.14.100
v4.14.101
v4.14.102
v4.14.103
v4.14.104
v4.14.105
v4.14.106
v4.14.107
v4.14.108
v4.14.109
v4.14.110
v4.14.111
v4.14.112
v4.14.113
v4.14.114
v4.14.115
v4.14.116
v4.14.117
v4.14.118
v4.14.119
v4.14.120
v4.14.121
v4.14.122
v4.14.123
v4.14.124
v4.14.125
v4.14.126
v4.14.127
v4.14.128
v4.14.129
v4.14.130
v4.14.131
v4.14.132
v4.14.133
v4.14.134
v4.14.135
v4.14.136
v4.14.137
v4.14.138
v4.14.139
v4.14.140
v4.14.141
v4.14.142
v4.14.143
v4.14.144
v4.14.145
v4.14.146
v4.14.147
v4.14.148
v4.14.149
v4.14.150
v4.14.151
v4.14.152
v4.14.153
v4.14.154
v4.14.155
v4.14.156
v4.14.157
v4.14.158
v4.14.159
v4.14.160
v4.14.161
v4.14.162
v4.14.163
v4.14.164
v4.14.165
v4.14.166
v4.14.167
v4.14.168
v4.14.169
v4.14.170
v4.14.171
v4.14.172
v4.14.173
v4.14.174
v4.14.175
v4.14.176
v4.14.177
v4.14.178
v4.14.179
v4.14.180
v4.14.181
v4.14.182
v4.14.183
v4.14.184
v4.14.185
v4.14.186
v4.14.187
v4.14.188
v4.14.189
v4.14.190
v4.14.191
v4.14.192
v4.14.193
v4.14.194
v4.14.195
v4.14.196
v4.14.197
v4.14.198
v4.14.199
v4.14.200
v4.14.201
v4.14.202
v4.14.203
v4.14.204
v4.14.205
v4.14.206
v4.14.207
v4.14.208
v4.14.209
v4.14.210
v4.14.211
v4.14.212
v4.14.213
v4.14.214
v4.14.215
v4.14.216
v4.14.217
v4.14.218
v4.14.219
v4.14.220
v4.14.221
v4.14.222
v4.14.223
v4.14.224
v4.14.225
v4.14.226
v4.14.227
v4.14.228
v4.14.229
v4.14.230
v4.14.231
v4.14.232
v4.14.233
v4.14.234
v4.14.235
v4.14.236
v4.14.237
v4.14.238
v4.14.239
v4.14.240
v4.14.241
v4.14.242
v4.14.243
v4.14.244
v4.14.245
v4.14.246
v4.14.247
v4.14.248
v4.14.249
v4.14.250
v4.14.251
v4.14.252
v4.14.253
v4.14.254
v4.14.255
v4.14.256
v4.14.257
v4.14.258
v4.14.259
v4.14.260
v4.14.261
v4.14.262
v4.14.263
v4.14.264
v4.14.265
v4.14.266
v4.14.267
v4.14.268
v4.14.269
v4.14.270
v4.14.271
v4.14.272
v4.14.273
v4.14.274
v4.14.275
v4.14.276
v4.14.277
v4.14.278
v4.14.279
v4.14.280
v4.14.281
v4.14.282
v4.14.283
v4.14.284
v4.14.285
v4.14.286
v4.14.287
v4.14.288
v4.14.289
v4.14.290
v4.14.291
v4.14.292
v4.14.293
v4.14.294
v4.14.295
v4.14.296
v4.14.297
v4.14.298
v4.14.299
v4.14.300
v4.14.301
v4.14.302
v4.14.303
v4.14.304
v4.14.305
v4.14.306
v4.14.307
v4.14.308
v4.14.309
v4.14.310
v4.14.311
v4.14.312
v4.14.313
v4.14.314
v4.14.315
v4.14.316
v4.14.317
v4.14.318
v4.14.319
v4.14.320
v4.14.321
v4.14.322
v4.14.323
v4.14.324
v4.14.325
v4.14.326
v4.14.327
v4.14.328
v4.14.329
v4.14.330
v4.14.331
v4.14.332
v4.14.333
v4.14.334
v4.14.335
v4.14.336
v4.14.77
v4.14.78
v4.14.79
v4.14.80
v4.14.81
v4.14.82
v4.14.83
v4.14.84
v4.14.85
v4.14.86
v4.14.87
v4.14.88
v4.14.89
v4.14.90
v4.14.91
v4.14.92
v4.14.93
v4.14.94
v4.14.95
v4.14.96
v4.14.97
v4.14.98
v4.14.99
v4.18.15
v4.18.16
v4.18.17
v4.18.18
v4.18.19
v4.18.20
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
v4.9.134
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
v4.9.150
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
v4.9.160
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
v4.9.170
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
v4.9.180
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
v4.9.190
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
v4.9.200
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
v4.9.210
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
v4.9.220
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
v4.9.230
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
v4.9.240
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
v4.9.250
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
v4.9.260
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
v4.9.270
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
v4.9.280
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
v4.9.290
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
v4.9.300
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
v4.9.310
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
v4.9.320
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
v4.9.330
v4.9.331
v4.9.332
v4.9.333
v4.9.334
v4.9.335
v4.9.336
v4.9.337
Linux / Kernel
Package
- Name
- Kernel
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced4.19.0Fixed5.10.265
- Type
- ECOSYSTEM
- Events
-
Introduced5.11.0Fixed5.15.216
- Type
- ECOSYSTEM
- Events
-
Introduced5.16.0Fixed6.1.183
- Type
- ECOSYSTEM
- Events
-
Introduced6.2.0Fixed6.6.152
- Type
- ECOSYSTEM
- Events
-
Introduced6.7.0Fixed6.12.104
- Type
- ECOSYSTEM
- Events
-
Introduced6.13.0Fixed6.18.45
- Type
- ECOSYSTEM
- Events
-
Introduced6.19.0Fixed7.1.9