# CVE-2026-64302: x86/mm: Fix freeing of PMD-sized vmemmap pages

> A memory leak in the Linux kernel x86/mm subsystem occurs when freeing PMD-sized vmemmap pages, potentially leading to resource exhaustion.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-64302, GHSA-rmr6-r8pg-m34q, ROOT-OS-UBUNTU-2204-CVE-2026-64302, UBUNTU-CVE-2026-64302

## What is CVE-2026-64302?

CVE-2026-64302 is a medium-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

x86/mm: Fix freeing of PMD-sized vmemmap pages

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 ]

## Which versions are affected by CVE-2026-64302?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64302?

Apply the vendor's patch.

## Is CVE-2026-64302 being exploited?

There is no known exploitation of CVE-2026-64302 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64302 and fix it if it is affected.

What it is: CVE-2026-64302 is a medium-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-64302 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-64302/ (Markdown: https://insights.sbomify.com/CVE-2026-64302/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64302
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64302
- OSV: https://osv.dev/vulnerability/CVE-2026-64302

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64302/
Summaries are generated and may contain mistakes; the official description above is the record.