CVE-2026-89956

Kernel memory corruption via unprotected mdev list

Published Sep 16, 2026 · Updated Sep 16, 2026

Race condition in Linux 6.0 s390 vfio-ap allows local users to corrupt kernel memory through concurrent mediated-device operations. The vfio_ap_mdev_probe path protects mdev_list with mdevs_lock instead of guests_lock, while status_show traverses the same list without guests_lock. Exploitation requires an IBM Z host with the vfio_ap driver and concurrent mediated-device creation, removal, or status access; successful racing causes use-after-free or kernel memory corruption.

CVSS severityUnavailable
Unscored
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux 6.0 s390 vfio-ap allows local users to corrupt kernel memory through concurrent mediated-device operations. The vfio_ap_mdev_probe path protects mdev_list with mdevs_lock instead of guests_lock, while status_show traverses the same list without guests_lock. Exploitation requires an IBM Z host with the vfio_ap driver and concurrent mediated-device creation, removal, or status access; successful racing causes use-after-free or kernel memory corruption.

The record

CVE
CVE-2026-89956
Published
Sep 16, 2026
Updated
Sep 16, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <0fd74477d05743d4cd9b25a3b667daa278d53b93
  2. Affected versionversion=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <647916988272fe5ecb4bb30cd02b51af9960618a
  3. Affected versionversion=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <7fa61c29850d05e40ca9ed41bfdf57673023f581
  4. Affected versionversion=6.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <0fd74477d05743d4cd9b25a3b667daa278d53b93; version=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <647916988272fe5ecb4bb30cd02b51af9960618a; version=2c1ee8983aa377fef4f725162f4f3aa5f9575d4a <7fa61c29850d05e40ca9ed41bfdf57673023f581; version=6.0

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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