CVE-2026-72069

Description

In the Linux kernel, the following vulnerability has been resolved: locking/rt: Fix the incorrect RCU protection in rt_spin_unlock() rt_spin_unlock() releases the RCU protection before unlocking the lock. That opens the door for the following UAF scenario: T1 T2 spin_lock(&p->lock); rcu_read_lock(); invalidate(p); p = rcu_dereference(ptr); rcu_assign_pointer(ptr, NULL); if (!p) return; spin_unlock(&p->lock); spin_lock(&p->lock) lock(&lock->lock); rcu_read_lock(); kfree_rcu(p); rcu_read_unlock(); .... spin_unlock(&p->lock) rcu_read_unlock(); // Ends grace period rcu_do_batch() kfree(p); UAF -> rt_mutex_cmpxchg_release(&lock->lock...) Regular spinlocks keep preemption disabled accross the unlock operation, which provides full RCU protection, but the RT substitution fails to resemble that. Same applies for the rwlock substitution. Move the rcu_read_unlock() invocation past the unlock operations to match the non-RT semantics. This makes it asymmetric vs. rt_xxx_lock(), but that's harmless as the caller needs to hold RCU read lock across the lock operation. The migrate_enable() call stays before the unlock operation because there is no per CPU operation in the unlock path which would require migration to be kept disabled.

Gravité et risque d'exploitation

CVE-2026-72069 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 0.73 %, ce qui la place devant 53.3 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, 7.1.5, 6.18.40, <=6.12.*, 6.12.101, 5.15.217, 0, <=7.1.*, <=6.6.*, <5.15, <3cfaac77b3c32ac3940df28866de263c3f45d24c, <1f0d56d3f1e88f20f6e46109402f8c15d59bac37, <af28d801cd2db4cc7378554499bd4a5d84a5517e, 0f383b6dc96e976dfbf2721b0bf10bd96103b341, 5.15, <=6.18.*, <83f9fb561c1c3917e19f95523dd933c7d30291aa, 6.1.184, <633cadbc0b8323f5cc140a285d2432089dbb534e, <=*, <=5.15.*, 6.6.148, 7.2, <9d1fcd64ab81200e02b7a6db5eb1da8e244e8289, <89038cc87d80c77e7aa6f42a64b2573b74af339f) 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/af28d801cd2db4cc7378554499bd4a5d84a5517e
• https://git.kernel.org/stable/c/9d1fcd64ab81200e02b7a6db5eb1da8e244e8289
• https://git.kernel.org/stable/c/3cfaac77b3c32ac3940df28866de263c3f45d24c
• https://git.kernel.org/stable/c/1f0d56d3f1e88f20f6e46109402f8c15d59bac37
• https://git.kernel.org/stable/c/633cadbc0b8323f5cc140a285d2432089dbb534e
• https://git.kernel.org/stable/c/83f9fb561c1c3917e19f95523dd933c7d30291aa
• https://git.kernel.org/stable/c/89038cc87d80c77e7aa6f42a64b2573b74af339f