# CVE-2026-43303: mm/page_alloc: clear page->private in free_pages_prepare()

> A use-after-free vulnerability in the Linux kernel swap subsystem allows local attackers to cause a system crash by exploiting stale page private data.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 8 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-86160, BELL-CVE-2026-43303, DEBIAN-CVE-2026-43303, GHSA-6fh9-96ww-pvwq, ROOT-OS-DEBIAN-12-CVE-2026-43303, ROOT-OS-DEBIAN-13-CVE-2026-43303, ROOT-OS-UBUNTU-2404-CVE-2026-43303, UBUNTU-CVE-2026-43303

## What is CVE-2026-43303?

CVE-2026-43303 is a high-severity use after free vulnerability in Linux kernel, published on 8 May 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:

mm/page_alloc: clear page->private in free_pages_prepare()

Several subsystems (slub, shmem, ttm, etc.) use page->private but don't
clear it before freeing pages.  When these pages are later allocated as
high-order pages and split via split_page(), tail pages retain stale
page->private values.

This causes a use-after-free in the swap subsystem.  The swap code uses
page->private to track swap count continuations, assuming freshly
allocated pages have page->private == 0.  When stale values are present,
swap_count_continued() incorrectly assumes the continuation list is valid
and iterates over uninitialized page->lru containing LIST_POISON values,
causing a crash:

  KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107]
  RIP: 0010:__do_sys_swapoff+0x1151/0x1860

Fix this by clearing page->private in free_pages_prepare(), ensuring all
freed pages have clean state regardless of previous use.

Weakness: CWE-416 (Use After Free), CWE-457 (Use of Uninitialized Variable)

## Which versions are affected by CVE-2026-43303?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43303?

Apply the vendor's patch.

## Is CVE-2026-43303 being exploited?

There is no known exploitation of CVE-2026-43303 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-2026-43303 and fix it if it is affected.

What it is: CVE-2026-43303 is a high-severity use after free vulnerability in Linux kernel, published on 8 May 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-2026-43303 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-2026-43303/ (Markdown: https://insights.sbomify.com/CVE-2026-43303/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43303
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43303
- OSV: https://osv.dev/vulnerability/CVE-2026-43303

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43303/
Summaries are generated and may contain mistakes; the official description above is the record.