CVE-2025-21745
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk12th percentile - higher than 12% of all known CVEs
Summary
In the Linux kernel, a subsystem refcount leakage of the @block_class was discovered in the blkcg_fill_root_iostats() function. The function iterates over devices using class_dev_iter_(init|next)() but does not end the iteration with class_dev_iter_exit(), causing a refcount leak.
Risk Assessment
The refcount leak can lead to system instability, kernel resource exhaustion, and potentially a denial of service (DoS) under prolonged system operation.
Recommendation
It is recommended to immediately update the Linux kernel to a version containing the fix, which adds the class_dev_iter_exit() call after iteration.
Original NVD description (English source)
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 ending the iterating with class_dev_iter_exit().