CVE-2026-93066x86/mm/pat: Take cpa_lock around large-page collapse
- —Not scoredno CVSS score yet
- 0.17%Exploitation in 30 daysEPSS · top 94% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Take cpa_lock around large-page collapse Loading and unloading modules concurrently on several CPUs on a KASAN build, with a short delay injected at the CPA page-table lookup to widen the window, faults within minutes: BUG: KASAN: use-after-free in __change_page_attr+0x7cc/0x7e0 Write of size 8 at addr ffff888181139718 by task modprobe ... The buggy address belongs to the physical page: pfn:0x181139 ... page_type: f2(table) cpa_collapse_large_pages() rebuilds a leaf PMD from its 4K PTEs and frees the old PTE-table pages, while __change_page_attr() fetches a PTE pointer from a lockless lookup_address_in_pgd_attr() and writes it with set_pte_atomic() only later. When module text is served from a shared large ROX mapping the two run on the same PMD: CPU A (module load) CPU B (module finalize) ------------------- ----------------------- execmem_make_temp_rw set_memory_nx __change_page_attr split 2M -> 4K table P kpte = &P[i] (lockless) execmem_restore_rox set_memory_rox (CPA_COLLAPSE) cpa_collapse_large_pages rebuild leaf PMD flush_tlb_all pagetable_free(P) set_pte_atomic(kpte, ...) -> writes into freed P P is a page-table page (page_type: table), reused at once, so the write corrupts whatever got the page next: a bad-pte or bad-page splat, or a fatal fault once P has been turned into read-only text. The flush_tlb_all() before the free does not close this: its IPI only serializes against page-table walkers that run with interrupts off (e.g. GUP-fast); the walk in __change_page_attr() runs with interrupts on, so nothing stops it from holding a stale pointer into P. Serialize the collapse - the PMD rebuild, TLB flush and PTE-table free - under cpa_lock, the same lock __change_page_attr() now takes unconditionally since commit ("x86/mm/pat: stop gating cpa_lock on debug_pagealloc_enabled()"), so a concurrent walker can no longer hold a pointer into a table the collapse is about to free.
Timeline
ID reserved
By Linux
Published
- 32 days later
· 32 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.17% · top 94% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 41d88484c71cd4f659348da41b7b5b3dbd3be1f6 – < 591b6fac9df3f43522e8ff6eed8662f8b6f1a124
- affected 41d88484c71cd4f659348da41b7b5b3dbd3be1f6 – < fb97d1d6c20692e15247fa5c8b894b2325e38aee
- affected 41d88484c71cd4f659348da41b7b5b3dbd3be1f6 – < 1aac65f3e651334259ecb2a5f5ddb81c01f02599
- affected 6.15
- unaffected < 6.15
- unaffected 6.18.52 – ≤ 6.18.*
- unaffected 7.2.6 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-82176 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-93066)Record last updated .