CVE-2026-43483
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Set/clear CR8 write interception when AVIC is (de)activated Explicitly set/clear CR8 write interception when AVIC is (de)activated to fix a bug where KVM leaves the interception enabled after AVIC is activated. E.g. if KVM emulates INIT=>WFS while AVIC is deactivated, CR8 will remain intercepted in perpetuity. On its own, the dangling CR8 intercept is "just" a performance issue, but combined with the TPR sync bug fixed by commit d02e48830e3f ("KVM: SVM: Sync TPR from LAPIC into VMCB::V_TPR even if AVIC is active"), the danging intercept is fatal to Windows guests as the TPR seen by hardware gets wildly out of sync with reality. Note, VMX isn't affected by the bug as TPR_THRESHOLD is explicitly ignored when Virtual Interrupt Delivery is enabled, i.e. when APICv is active in KVM's world. I.e. there's no need to trigger update_cr8_intercept(), this is firmly an SVM implementation flaw/detail. WARN if KVM gets a CR8 write #VMEXIT while AVIC is active, as KVM should never enter the guest with AVIC enabled and CR8 writes intercepted. [Squash fix to avic_deactivate_vmcb. - Paolo]
Gravité et risque d'exploitation
CVE-2026-43483 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.16 %, ce qui la place devant 5.0 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 6.12.78, 0, 7.0, <816fa1dfae4532e851b1fe6b2434c753ecbd86c7, 6.18.19, <=6.6.*, <737410b32bd615b321da4fbeda490351b9af5e8b, <=6.19.*, <a4123fe5d9122eef9852e4921f7cc463420f30d4, <87d0f901a9bd8ae6be57249c737f20ac0cace93d, <ba3bca40f9f25c053f69413e5f4a41dd0fd762bf, <01651e7751edbbc0fb4598f8367a3dabcfc8c182, 6.19.9, 4.7, <=6.18.*, 6.1.167, 3bbf3565f48ce3999b5a12cde946f81bd4475312, <=*, <4.7, 6.6.130) 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/a4123fe5d9122eef9852e4921f7cc463420f30d4
- https://git.kernel.org/stable/c/816fa1dfae4532e851b1fe6b2434c753ecbd86c7
- https://git.kernel.org/stable/c/01651e7751edbbc0fb4598f8367a3dabcfc8c182
- https://git.kernel.org/stable/c/ba3bca40f9f25c053f69413e5f4a41dd0fd762bf
- https://git.kernel.org/stable/c/737410b32bd615b321da4fbeda490351b9af5e8b
- https://git.kernel.org/stable/c/87d0f901a9bd8ae6be57249c737f20ac0cace93d