# CVE-2026-89653

## Summary

- **CVE ID:** CVE-2026-89653
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## Description

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

ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

MDSMap export_targets entries are monitor controlled. check_new_map()
uses each entry as a bit number in a fixed stack bitmap, so a rank
outside the protocol namespace can make set_bit() write past the end of
the array.

Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not
validate against possible_max_rank here because maps may legitimately
reference ranks beyond a temporarily reduced max_mds.

## Affected Products

- Linux — Linux (d517b3983dd3106ca92d6c5d0d09415a4a09481c)
- Linux — Linux (5.15)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/736adee11af36e407ed902264f8b2fb5cf94b62f)
- [CNA](https://git.kernel.org/stable/c/4d298880f82c42383b36946bafde7ccf4d804c9b)
- [CNA](https://git.kernel.org/stable/c/96c3f5fbb0d5386e7111426f047f98cec4586674)
- [CNA](https://git.kernel.org/stable/c/aedc9053d909508a5f56c3f49f885fc030df4730)
- [CNA](https://git.kernel.org/stable/c/3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe)
- [CNA](https://git.kernel.org/stable/c/8c823bbab3c24e657469a84db96902ba82d4e8bb)
- [CNA](https://git.kernel.org/stable/c/c4addccd05bacbef2144b4db14853d0308a218ac)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.51%
- **EPSS Percentile:** 42.3

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