CVE-2026-89961

Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population vmemmap_populate_compound_pages() uses addr_pfn to determine the PFN offset within a compound page and to decide whether the current vmemmap slot should be populated as a head page mapping or should reuse a tail page mapping. However, addr_pfn is advanced manually in parallel with addr. The loop itself progresses in vmemmap address space, so each PAGE_SIZE step in addr covers PAGE_SIZE / sizeof(struct page) struct page slots. Since addr_pfn is compared against nr_pages in data-PFN units, it should advance by the same number of PFNs. The existing manual increments do not match that and therefore do not reliably track the PFN corresponding to the current addr. As a result, pfn_offset can be computed from the wrong PFN and the code can make the head/tail decision for the wrong compound-page position. Fix this by deriving addr_pfn directly from the current vmemmap address instead of carrying it as loop state.

Gravité et risque d'exploitation

CVE-2026-89961 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 0.18 %, ce qui la place devant 6.6 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.12.*, <7968852a7ca3ce81477ec5b4494a28d612f35a97, 0, 6.18.51, <6.6, <=6.6.*, 7.2.5, 6.6.157, <b96be860673f9fbbf12cdadb0b25fc4d6d4d207f, 6.6, <9c914b7a0bd18834505c65f22225ce22c152b2d9, <=6.18.*, <=7.2.*, 6.12.110, <89a4ae32764172468dea303eb6ae90fe6c859712, <=*, <e163c7184acf36ac20a248498f4a16016057ca01, f2b79c0d79683d552369bb9a7282c1f0226fc566, 7.3) 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/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f
• https://git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01
• https://git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9
• https://git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97
• https://git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712