Heimdall Security Logo

CVE-2026-72043

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.1 · Élevée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, 7.1.5, 6.18.40, <=6.12.*, <e483da960892c41fa7f0cf0d2fc2410d65a483d6, 0, <=7.1.*, 5.19, 6.1.178, <39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9, 6.12.97, <=6.6.*, <=6.18.*, <76f88650763a35cbf1384c65d66d096fa31cc58d, 6.6.145, <018e9828eb523c638fa3d9bdf0fd4956b74555b2, <5.19, <a65f49b6f7ece756394f8f0e85570020e7fd0e35, <=*, 09cfefb7fa70c3af011b0db0a513fd80b2f18abc, 7.2, <e8a916579e427af32f2de8213dfa23c5df6e6664

Description

In the Linux kernel, the following vulnerability has been resolved: LoongArch: Fix missing dirty page tracking in {pte,pmd}_wrprotect() When hardware page table walker (PTW) is enabled on LoongArch, the CPU may set _PAGE_DIRTY directly in the page table entry during a write TLB miss, without going through the software TLB store handler. The software TLB store handler (tlbex.S:254) sets both _PAGE_DIRTY and_PAGE_MODIFIED together: ori t0, t0, (_PAGE_VALID | _PAGE_DIRTY | _PAGE_MODIFIED) Since hardware PTW only sets _PAGE_DIRTY, the software-only bit, i.e. _PAGE_MODIFIED is left unchanged. This creates a window where a PTE has _PAGE_DIRTY set (hardware knows the page is dirty) but _PAGE_MODIFIED clear (software is unaware). When fork()/clone() triggers copy-on-write, __copy_present_ptes() calls pte_wrprotect(), which unconditionally clears both the _PAGE_WRITE and _PAGE_DIRTY bits: pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_DIRTY); Since _PAGE_MODIFIED was never set, the dirtiness information is lost completely. Subsequently, when memory pressure triggers page reclaim, page_mkclean() / try_to_unmap() sees the page as clean (i.e. pte_dirty() returns false) and the page may be freed without writeback, causing data corruption. Fix this by propagating the _PAGE_DIRTY bit to the _PAGE_MODIFIED bit in both pte_wrprotect() and pmd_wrprotect() before clearing writeable bits: if (pte_val(pte) & _PAGE_DIRTY) pte_val(pte) |= _PAGE_MODIFIED; The pmd_wrprotect() fix handles the CONFIG_TRANSPARENT_HUGEPAGE case, where pmd entries need the same treatment. This ensures the software dirty tracking bit (checked by pte_dirty() and pmd_dirty(), which read both the _PAGE_DIRTY and _PAGE_MODIFIED bits) is preserved across fork COW write-protection. The issue was found by the LTP madvise09 test case, which exercises page reclaim after "madvise(MADV_FREE), write and fork" operation sequence on private anonymous mappings.

Gravité et risque d'exploitation

CVE-2026-72043 obtient un score CVSS de 7.1/10, 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 6.2 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, 7.1.5, 6.18.40, <=6.12.*, <e483da960892c41fa7f0cf0d2fc2410d65a483d6, 0, <=7.1.*, 5.19, 6.1.178, <39bb21a4bff0d70058bf752d7b5aa2e2ccc864a9, 6.12.97, <=6.6.*, <=6.18.*, <76f88650763a35cbf1384c65d66d096fa31cc58d, 6.6.145, <018e9828eb523c638fa3d9bdf0fd4956b74555b2, <5.19, <a65f49b6f7ece756394f8f0e85570020e7fd0e35, <=*, 09cfefb7fa70c3af011b0db0a513fd80b2f18abc, 7.2, <e8a916579e427af32f2de8213dfa23c5df6e6664) 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

Rechercher une autre CVE