---
title: "CVE-2026-90191: Linux kernel mailbox riscv-sbi-mpxy - Buffer Validation Vulnerability"
description: "Linux kernel mailbox riscv-sbi-mpxy contains a buffer validation vulnerability caused by improper validation of RPMI notification lengths, letting attackers cause memory corruption or denial of service, exploit requires crafted shared memory input."
url: https://panop.io/threat-heartbeat/CVE-2026-90191/
---

# CVE-2026-90191 Linux kernel mailbox riscv-sbi-mpxy - Buffer Validation Vulnerability

Linux kernel mailbox riscv-sbi-mpxy contains a buffer validation vulnerability caused by improper validation of RPMI notification lengths, letting attackers cause memory corruption or denial of service, exploit requires crafted shared memory input.

CVSS base score 8.4 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.19% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-90191)

## Details

Type

Buffer Validation Vulnerability

Impact

Denial Of Service

CVSS vector

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

Published

17 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-2026-90191](https://nvd.nist.gov/vuln/detail/CVE-2026-90191)
- [https://git.kernel.org/stable/c/11d5af151bcbe78f5a579e0faecd3be9cea0399a](https://git.kernel.org/stable/c/11d5af151bcbe78f5a579e0faecd3be9cea0399a)
- [https://git.kernel.org/stable/c/c7bc5e7677bcda7a446d63b989cfaa3fe91d6b76](https://git.kernel.org/stable/c/c7bc5e7677bcda7a446d63b989cfaa3fe91d6b76)
- [https://git.kernel.org/stable/c/cbc24bce70dfd91c7b2f53b4fa896e9a4b6d6a6b](https://git.kernel.org/stable/c/cbc24bce70dfd91c7b2f53b4fa896e9a4b6d6a6b)

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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

Panop answers these inside your environment, for this CVE and every other finding.

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