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CVE-2026-64302
x86/mm: Fix freeing of PMD-sized vmemmap pages
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem arch/x86. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-64302 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Commit bf9e4e30f353 ("x86/mm: use pagetable_free()"), switched from freeing non-boot page tables through __free_pages() to pagetable_free(). However, the function is also called to free vmemmap pages. Given that vmemmap pages are not page tables, already the page_ptdesc(page) is wrong. But worse, pagetable_free() calls: __free_pages(page, compound_order(page)); Since vmemmap pages are not compound pages (see vmemmap_alloc_block()) -- except for HVO, which doesn't apply here -- only first page of a PMD-sized vmemmap page is freed, leaking the other ones. Fix it by properly decoupling pagetable and vmemmap freeing. free_pagetable() no longer has to mess with SECTION_INFO, as only the vmemmap is marked like that in register_page_bootmem_memmap(). The indentation in remove_pmd_table() is messed up. Fix that while touching it. Bootmem info handling will soon be fixed up. For now, handle it similar to free_pagetable(), just avoiding the ifdef. [ dhansen: changelog munging. More imperative voice ]
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/x86/mm/init_64.c
- What this is
- X86 MMMAINTAINERS section matched on arch/x86/mm/ · linux-kernel@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-07-25 (3 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.16%, higher than 4.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- arch/x86
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.18.7 | 6.18.39 | add1e4112e00 |
| 6.19 | 7.1.4 | 03f6ecbc446c |
| 6.19 | 7.2 | 39406c05f8f1 |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-64302, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.