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CVE-2025-21850: linux kernel vulnerability
CVE-2025-21850: critical vulnerability affecting linux kernel. Check CVSS, KEV status, business impact and recommended administrator actions.
- CVSS
- 9.8 CRITICAL
- EPSS
- 34.37%
- Known exploited
- not in KEV
- Product
- linux kernel
What is known
In the Linux kernel, the following vulnerability has been resolved: nvmet: Fix crash when a namespace is disabled The namespace percpu counter protects pending I/O, and we can only safely diable the namespace once the counter drop to zero. Otherwise we end up with a crash when running blktests/nvme/058 (eg for loop transport): [ 2352.930426] [ T53909] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN PTI [ 2352.930431] [ T53909] KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] [ 2352.930434] [ T53909] CPU: 3 UID: 0 PID: 53909 Comm: kworker/u16:5 Tainted: G W 6.13.0-rc6 #232 [ 2352.930438] [ T53909] Tainted: [W]=WARN [ 2352.930440] [ T53909] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 [ 2352.930443] [ T53909] Workqueue: nvmet-wq nvme_loop_execute_work [nvme_loop] [ 2352.930449] [ T53909] RIP: 0010:blkcg_set_ioprio+0x44/0x180 as the queue is already torn down when calling submit_bio(); So we need to init the percpu counter in nvmet_ns_enable(), and wait for it to drop to zero in nvmet_ns_disable() to avoid having I/O pending after the namespace has been disabled.
Business impact
Successful exploitation of CVE-2025-21850, a critical vulnerability (CVSS 9.8) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.
Recommended administrator action
Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.