---
title: "CVE-2026-89656: Linux kernel libceph - Out of Bounds Write"
description: "Linux kernel libceph contains an out-of-bounds write caused by mismatched CRUSH bucket ids in crush_decode(), letting attackers trigger memory corruption, exploit requires a malformed CRUSH map."
url: https://panop.io/threat-heartbeat/CVE-2026-89656/
---

# CVE-2026-89656 Linux kernel libceph - Out of Bounds Write

Linux kernel libceph contains an out-of-bounds write caused by mismatched CRUSH bucket ids in crush\_decode(), letting attackers trigger memory corruption, exploit requires a malformed CRUSH map.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

EPSS

0.51% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89656)

## Details

Type

Out of Bounds Write

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Published

11 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-89656](https://nvd.nist.gov/vuln/detail/CVE-2026-89656)
- [https://git.kernel.org/stable/c/ee59040d6ed1a5f8d10d27174b8f32c90ca8e89a](https://git.kernel.org/stable/c/ee59040d6ed1a5f8d10d27174b8f32c90ca8e89a)
- [https://git.kernel.org/stable/c/00562ccd4e88d092b9b851df50fad20442bfeb24](https://git.kernel.org/stable/c/00562ccd4e88d092b9b851df50fad20442bfeb24)
- [https://git.kernel.org/stable/c/3516a4131c4e45d62ee4e42e82c36930e8c1fbbd](https://git.kernel.org/stable/c/3516a4131c4e45d62ee4e42e82c36930e8c1fbbd)
- [https://git.kernel.org/stable/c/3cde4a8302301679937474a5f7a851394cc1bd11](https://git.kernel.org/stable/c/3cde4a8302301679937474a5f7a851394cc1bd11)
- [https://git.kernel.org/stable/c/79900d978158b2d80eef952fc41b9e4dc58d7b83](https://git.kernel.org/stable/c/79900d978158b2d80eef952fc41b9e4dc58d7b83)
- [https://git.kernel.org/stable/c/4aeb93daadf388e72073abc204312dd364eeb30a](https://git.kernel.org/stable/c/4aeb93daadf388e72073abc204312dd364eeb30a)
- [https://git.kernel.org/stable/c/6e5c6ce252b1eccfd41670a5cf95ab44f7ba7022](https://git.kernel.org/stable/c/6e5c6ce252b1eccfd41670a5cf95ab44f7ba7022)
- [https://git.kernel.org/stable/c/baad5875fdd2f5e248250fc3519bb045d64f1716](https://git.kernel.org/stable/c/baad5875fdd2f5e248250fc3519bb045d64f1716)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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