CVE-2026-72390

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: Introduce slaves_lock to avoid race condition and UAF The teql master->slaves singly linked list is not protected against multiple writes. It can be mod'ed concurently from teql_master_xmit(), teql_dequeue(), teql_init() and teql_destroy() without holding any list lock or RCU protection. zdi-disclosures@trendmicro.com has demonstrated that the qdisc is freed after an RCU grace period, but teql_master_xmit() running on another CPU can still hold a stale pointer into the list, resulting in a slab-use-after-free: BUG: KASAN: slab-use-after-free in teql_master_xmit+0xf0f/0x16b0 Read of size 8 at addr ffff888013fb0440 by task poc/332 Freed 512-byte region [ffff888013fb0400, ffff888013fb0600) (kmalloc-512) The fix? Add a per-master slaves_lock spinlock that serializes all mutations of master->slaves and the NEXT_SLAVE() links in teql_destroy() and teql_qdisc_init(). teql_master_xmit() also takes the same slaves_lock around those updates. Annotate master->slaves and the per-slave ->next pointer with __rcu and use the appropriate RCU accessors everywhere they are touched: rcu_assign_pointer() on the writer side (under slaves_lock), rcu_dereference_protected() for the writer-side loads (also under slaves_lock), rcu_dereference_bh() for the loads in teql_master_xmit() and rtnl_dereference() for the loads in teql_master_open()/teql_master_mtu(), which run under RTNL. Pair this with rcu_read_lock_bh()/rcu_read_unlock_bh() around the list traversal in teql_master_xmit(), so that readers either observe a fully linked list or are deferred until the in-flight mutation completes. The two early-return paths in teql_master_xmit() are updated to release the RCU-bh read-side critical section before returning, since leaving it held would disable BH on that CPU for good.

Gravité et risque d'exploitation

CVE-2026-72390 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.17 %, ce qui la place devant 6.5 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <11402e6e18e96df615cbcc58157818dd604b23ff, <=6.1.*, 6.18.40, <=6.12.*, 7.1.5, 2.6.12, <9b7d05cbaa60108642402100efa6aa288dd33023, <e5b811fe793166aecc59b085c1b7c31262ef2316, 0, <=7.1.*, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 6.1.178, 6.12.97, <=6.6.*, <=6.18.*, 6.6.145, <b26aa9d993537a4c3167d8ceead3b7c69c3a0aac, <03c67781254c574ae7fa75e881239a78473bdf42, <=*, <735567bde7401f82b064f9f107b52ee1bf84ed8c, 7.2) 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/03c67781254c574ae7fa75e881239a78473bdf42
• https://git.kernel.org/stable/c/735567bde7401f82b064f9f107b52ee1bf84ed8c
• https://git.kernel.org/stable/c/11402e6e18e96df615cbcc58157818dd604b23ff
• https://git.kernel.org/stable/c/9b7d05cbaa60108642402100efa6aa288dd33023
• https://git.kernel.org/stable/c/b26aa9d993537a4c3167d8ceead3b7c69c3a0aac
• https://git.kernel.org/stable/c/e5b811fe793166aecc59b085c1b7c31262ef2316