CVE-2022-49300: nbd: fix race between nbd_alloc_config() and module removal
Vulnerability summary
CVE-2022-49300 is a medium (CVSS 4.7) vulnerability in linux. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.9% of scored vulnerabilities.
Not severe (CVSS 4.7, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 7 · Related 7Timeline
- 26-02-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: nbd: fix race between nbd_alloc_config() and module removal When nbd module is being removing, nbd_alloc_config() may be called concurrently by nbd_genl_connect(), although try_module_get() will return false, but nbd_alloc_config() doesn't handle it. The race may lead to the leak of nbd_config and its related resources (e.g, recv_workq) and oops in nbd_read_stat() due to the unload of nbd module as shown below: BUG: kernel NULL pointer dereference, address: 0000000000000040 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Workqueue: knbd16-recv recv_work [nbd] RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd] Call Trace: recv_work+0x3b/0xb0 [nbd] process_one_work+0x1ed/0x390 worker_thread+0x4a/0x3d0 kthread+0x12a/0x150 ret_from_fork+0x22/0x30 Fixing it by checking the return value of try_module_get() in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV), assign nbd->config only when nbd_alloc_config() succeeds to ensure the value of nbd->config is binary (valid or NULL). Also adding a debug message to check the reference counter of nbd_config during module removal.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated4.7MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated4.7MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- NVDNIST4.7MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.19% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-362Concurrent Execution using Shared Resource with Improper SynchronizationThe product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
- CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu112 products
- linuxAll versions (No fix recorded) | < 4.15.0-192.203 | < 5.4.0-126.142 | < 5.15.0-48.54
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1140.151 | < 5.4.0-1085.92 | < 5.15.0-1020.24
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 165cf2e0019fa6cedc75b456490c41494c34abb4 | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 2573f2375b64280be977431701ed5d33b75b9ad0 | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 8a7da4ced236ce6637fe70f14ca18e718d4bf9e9 | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 122e4adaff2439f1cc18cc7e931980fa7560df5c | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 71c142f910da44421213ade601bcbd23ceae19fa | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < 2888fa41985f93ed0a6837cfbb06bcbfd7fa2314 | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < d09525720dd5201756f698bee1076de9aefd4602 | ≥ 5ea8d10802ec4c153a6e21eebaf412e2abd29736, < c55b2b983b0fa012942c3eb16384b2b722caa810 | 4.12
- linux_kernel< 4.14.283 | ≥ 4.15, < 4.19.247 | ≥ 4.20, < 5.4.198 | ≥ 5.5, < 5.10.122 | ≥ 5.11, < 5.15.47 | ≥ 5.16, < 5.17.15 | ≥ 5.18, < 5.18.4
Debian1 product
- linux< 5.18.5-1
3 vendors · 115 products
