CVE-2025-21745
Linux Kernel 5.9 – 6.1.129
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2025-21745 is a medium-severity an unspecified weakness vulnerability in Linux Linux Kernel. Its CVSS base score is 5.5 (Medium).
Operationally, ranked at the 14th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-2 (Flaw Remediation) and CM-7 (Least Functionality) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-5179
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix class @block_class's subsystem refcount leakage blkcg_fill_root_iostats() iterates over @block_class's devices by class_dev_iter_(init|next)(), but does not end iterating with class_dev_iter_exit(), so causes the class's subsystem refcount leakage. Fix by…
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ending the iterating with class_dev_iter_exit().
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the kernel patch that adds the missing class_dev_iter_exit() call to eliminate the blk-cgroup refcount leak.
Restricts enabling of block cgroup and related I/O accounting features that trigger the defective class_dev_iter path.
Memory-protection mechanisms can contain secondary effects of the unbounded subsystem refcount growth caused by the leak.