CVE-2026-93186Hinoki check available

Kernel panic via unbounded mailbox output allocation

Published Sep 17, 2026 · Updated Sep 17, 2026

Unbounded allocation in Linux CXL mailboxes allows local users to crash the kernel via an oversized output-size request. CXL_MEM_SEND_COMMAND leaves out.size unbounded, and cxl_mbox_cmd_ctor() passes it to kvzalloc() without limiting allocation to the mailbox payload size. Access to the CXL device ioctl is required; values above INT_MAX trigger a warning and kernel taint, with a kernel panic when panic_on_warn=1.

CVSS severity2.3
Low
EPSS probability0.19%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Unbounded allocation in Linux CXL mailboxes allows local users to crash the kernel via an oversized output-size request. CXL_MEM_SEND_COMMAND leaves out.size unbounded, and cxl_mbox_cmd_ctor() passes it to kvzalloc() without limiting allocation to the mailbox payload size. Access to the CXL device ioctl is required; values above INT_MAX trigger a warning and kernel taint, with a kernel panic when panic_on_warn=1.

The record

CVE
CVE-2026-93186
Published
Sep 17, 2026
Updated
Sep 17, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=5.12
  2. Affected versionversion=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <31d4841eca7c4b75751ca96d24339e19303337f2
  3. Affected versionversion=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <8a13db9f899d149c3aab24abcb668121cfda5a4f
  4. Affected versionversion=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <b4e11c731d6bee3b87315e055a1ca417c92dc1fc
  5. Affected versionversion=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <f5d2bbf0300f46307948864fbb97bce5097f4fe2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <31d4841eca7c4b75751ca96d24339e19303337f2; version=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <8a13db9f899d149c3aab24abcb668121cfda5a4f; version=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <b4e11c731d6bee3b87315e055a1ca417c92dc1fc; version=583fa5e71caeb79e04e477e9837e2f7fa53b71e4 <f5d2bbf0300f46307948864fbb97bce5097f4fe2

Published CVSS scores

2.1TenableAV:L/AC:L/Au:N/C:N/I:N/A:P
5.5TenableCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
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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