# CVE-2026-89503

## Summary

- **CVE ID:** CVE-2026-89503
- **Severity:** HIGH
- **CVSS Score:** 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## Description

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

ring-buffer: Fix subbuf resize race with ring_buffer_alloc_read_page()

ring_buffer_alloc_read_page() is racy with ring_buffer_subbuf_order_set,
it can allocate a reader page with an outdated order. This isn't a big
issue, the user can still re-allocate a new reader page and try again.

However, what is more problematic is if the value of subbuf_order
changes in the middle of ring_buffer_alloc_read_page(). In that case,
bpage->order might not match the actual allocated memory.

Use bpage->order for the allocation to prevent this race.

## Affected Products

- Linux — Linux (bce761d757452ba5eb77e11fecc37a04b67494e7)
- Linux — Linux (6.8)
- Linux — Linux (0)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/2dc510957fe8fd098ab3c3147ebdf34d00cd2734)
- [CNA](https://git.kernel.org/stable/c/53106e9262a310ef2c9a9321168c03705940c678)
- [CNA](https://git.kernel.org/stable/c/e743527c5bfdceda1095bc0a9e596e2aebb6a9c3)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.16%
- **EPSS Percentile:** 5.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._