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CVE-2026-52946

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.5 · Élevée
EPSS 0.5%
Linux•Linux•Versions : <=6.1.*, <=7.0.*, <=6.12.*, 6.12.94, 2.6.12, <00633c4683828acd5256fa8d5163f440d74bbe71, <32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33, 0, <bfcc8e8d8a495bb34cae9e620adfb75fb13a3954, <=7.1.*, <897d6a7247739fb1528f98c575df4f2e5de7f994, 6.1.176, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 5.15.210, <36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed, <=5.10.*, <=6.6.*, 7.0.13, 6.18.36, <=6.18.*, <20a93e397abe850c49b6fa0e8cc827b5f634a8f5, <=*, <54626335ea4174ab2d9a183b511d825f6765e47b, <=5.15.*, <1bee417678f1135e35b25a37734db46aa94258d2, 6.6.143, <b5fa9e32fb6718f70c986ee14dd5d01b4846f331, 7.2, 5.10.259, 7.1.1

Description

In the Linux kernel, the following vulnerability has been resolved: fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio() and send_sigurg() when a process group receives a signal. When FASYNC is configured for a process group (PIDTYPE_PGID), both functions use read_lock(&tasklist_lock) to traverse the task list. However, they are frequently called from softirq context: - send_sigio() via input_inject_event -> kill_fasync - send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ) The deadlock is caused by the rwlock writer fairness mechanism: 1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait(). 2. CPU 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all new readers. 3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception). 4. The softirq calls send_sigurg() and attempts to acquire read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting. Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a potential remote denial of service vector via TCP URG packets. Lockdep splat: ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [...] Chain exists of: &dev->event_lock --> &f_owner->lock --> tasklist_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable(); lock(&dev->event_lock); lock(&f_owner->lock); <Interrupt> lock(&dev->event_lock); *** DEADLOCK ***

Gravité et risque d'exploitation

CVE-2026-52946 obtient un score CVSS de 7.5/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.47 %, ce qui la place devant 39.1 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=7.0.*, <=6.12.*, 6.12.94, 2.6.12, <00633c4683828acd5256fa8d5163f440d74bbe71, <32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33, 0, <bfcc8e8d8a495bb34cae9e620adfb75fb13a3954, <=7.1.*, <897d6a7247739fb1528f98c575df4f2e5de7f994, 6.1.176, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 5.15.210, <36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed, <=5.10.*, <=6.6.*, 7.0.13, 6.18.36, <=6.18.*, <20a93e397abe850c49b6fa0e8cc827b5f634a8f5, <=*, <54626335ea4174ab2d9a183b511d825f6765e47b, <=5.15.*, <1bee417678f1135e35b25a37734db46aa94258d2, 6.6.143, <b5fa9e32fb6718f70c986ee14dd5d01b4846f331, 7.2, 5.10.259, 7.1.1) 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

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