CVE-2026-89548

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

SUNRPC: always drain cache_cleaner before destroying a cache_detail

sunrpc_destroy_cache_detail() only cancels the global cache_cleaner

delayed_work when cache_list is empty. During per-netns teardown

cache_list is never empty because init_net's caches remain registered,

so the cancel never fires. After unlink, the caller proceeds to

cache_destroy_net() which kfrees the cache_detail while cache_clean()

may still hold a dangling pointer to it. The result is a

use-after-free: cache_dequeue() takes cd->queue_lock on freed memory,

and cache_put() dereferences cd->cache_put as a function pointer from

freed slab.

Drop the list_empty guard so that cancel_delayed_work_sync() always

runs, ensuring any in-flight cache_clean() completes before the

cache_detail is freed. Re-arm the cleaner afterwards if other caches

are still registered.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References