Medium [CVE-2026-72404] fix UAF in cleanup_bearer due to premature dst_cache_destroy
This medium-severity Red Hat Linux advisory covers CVE-2026-72404 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: fix UAF in cleanup_bearer() due to premature dst_cache_destroy() TIPC UDP media bearer teardown calls dst_cache_destroy() on its replicast caches before calling synchronize_net() to wait for concurrent RCU readers (transmitters) to finish: static void cleanup_bearer(struct work_struct *work) {... list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) { dst_cache_destroy(&rcast->dst_cache); list_del_rcu(&rcast->list); kfree_rcu(rcast, rcu); }... dst_cache_destroy(&ub->rcast.dst_cache); udp_tunnel_sock_release(ub->sk); synchronize_net();... } This is highly buggy because dst_cache_destroy() immediately frees the per-CPU cache memory (free_percpu()) and releases the cached dst entries without any synchronization.
If a concurrent transmitter (e.g., tipc_udp_xmit()) is running on another CPU under RCU protection, it can call dst_cache_get() concurrently, leading to: 1. Use-After-Free on the per-CPU cache pointer itself (crash).
2. "rcuref - imbalanced put()" warning if it attempts to release a dst that was concurrently released by dst_cache_destroy().
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 58 minutes ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 58 minutes ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 58 minutes ago·verify at source
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