CVE-2026-64541

Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done.

Gravité et risque d'exploitation

CVE-2026-64541 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.56 %, ce qui la place devant 45.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, 7.1.5, 6.18.40, <=6.12.*, <ce5aa8084329351086894aa34d77e40301d5bd3d, <9d160b35cc34a2ba8229d07651468a7848325135, 0, <=7.1.*, <8de4f665d0febfb92803dece377791a563fc7041, d7b0e37c1ac152905b18a5b9506179091a35b0b6, <472e9d7c0d5b03be3ff91ff941f57da822b031bc, 6.1.178, <1951bffbc6493ec34cff3956b29d4bc6606904a6, <=5.10.*, <=6.6.*, 6.12.97, <=6.18.*, 5.15.212, 6.6.145, 5.10.261, <4.18, 4.18, <=*, <=5.15.*, <647b19e5cc145a2f1f685ae8ff3805a17356888c, <8145b432136285e01091815b48ceb2dae261f262, 7.2, <3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/8de4f665d0febfb92803dece377791a563fc7041
• https://git.kernel.org/stable/c/8145b432136285e01091815b48ceb2dae261f262
• https://git.kernel.org/stable/c/1951bffbc6493ec34cff3956b29d4bc6606904a6
• https://git.kernel.org/stable/c/647b19e5cc145a2f1f685ae8ff3805a17356888c
• https://git.kernel.org/stable/c/472e9d7c0d5b03be3ff91ff941f57da822b031bc
• https://git.kernel.org/stable/c/3bfb96d9bc6a7ed0b99c7db329cc2e22a28d84bb
• https://git.kernel.org/stable/c/ce5aa8084329351086894aa34d77e40301d5bd3d
• https://git.kernel.org/stable/c/9d160b35cc34a2ba8229d07651468a7848325135