CVE-2026-64561

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages. Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages. Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.

Gravité et risque d'exploitation

CVE-2026-64561 obtient un score CVSS de 8.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.35 %, ce qui la place devant 26.8 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, 6.12.101, <65c4f7a1028cf01a93a2762d679c289810ede990, 0, <bce0d3c26e2c761a4bf43c8949f333fc7374eb2d, <=7.1.*, <f3477a6a4164f15287444eda685b5f6405dbd1e5, <62ef67af1878fa2cd066642f2f59e33ade95f637, <0026dbb7de8ea76e97d6edf42fc3cc084564e2bf, <35e77467610c4a37cb0ff54ee56b85f73b1f5700, <=6.6.*, 6.18.42, 7.1.6, 6.1.183, <=6.18.*, 5.9, <5.9, <2abd5287f08319fa35764566b15c6e22cb1068db, <=*, <=5.15.*, 6.6.148, 7.2, f95eec9bed76d42194c23153cb1cc8f186bf91cb, 5.15.218) 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/62ef67af1878fa2cd066642f2f59e33ade95f637
• https://git.kernel.org/stable/c/65c4f7a1028cf01a93a2762d679c289810ede990
• https://git.kernel.org/stable/c/35e77467610c4a37cb0ff54ee56b85f73b1f5700
• https://git.kernel.org/stable/c/0026dbb7de8ea76e97d6edf42fc3cc084564e2bf
• https://git.kernel.org/stable/c/f3477a6a4164f15287444eda685b5f6405dbd1e5
• https://git.kernel.org/stable/c/bce0d3c26e2c761a4bf43c8949f333fc7374eb2d
• https://git.kernel.org/stable/c/2abd5287f08319fa35764566b15c6e22cb1068db
• https://github.com/V4bel/Zapscape