CVE-2026-64181
Vulnérabilité élevée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special() On x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a "WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d", from the VM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by "BUG: Bad rss-counter state"s, then later "BUG: Bad page state"s when reclaim gets to call shrink_huge_zero_folio_scan(). It's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and indeed, whereas pte_special() and pte_mkspecial() are subject to a dedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial() are subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on any 32-bit architecture. While the problem was exposed through commit d80a9cb1a64a ("mm/huge_memory: add and use normal_or_softleaf_folio_pmd()"), it was an oversight in commit af38538801c6 ("mm/memory: factor out common code from vm_normal_page_*()") and would result in other problems: * huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and numamaps as file-backed THP * folio_walk_start() returning the folio even without FW_ZEROPAGE set. Callers seem to tolerate that, though. ... and triggering the VM_WARN_ON_ONE(), although never reported so far. To fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider whether pmd_special/pud_special is actually implemented.
Gravité et risque d'exploitation
CVE-2026-64181 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 6.3 % des CVE référencées.
Que faire ?
- Vérifiez si Linux (versions <c0c6ccd9828c3a1950623b546fa57292a77b5c73, <=7.0.*, <=*, 6.18.34, 6.18, 7.1, <=6.18.*, af38538801c6a97565b44700ee6695d7d60ad779, 7.0.11, 0, <6.18, <62153767e8fc3889bc6508e9ffe927aaf64c4334, <9052ea2ee2233be5d4786b8909151ca2bfbedf99) 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.