CVE-2026-45865

Kernel stack disclosure via uninitialized I2C reads

Published May 27, 2026 · Updated May 27, 2026

Information disclosure in the Linux Kernel MCTP-over-I2C driver allows local users to read an uninitialized kernel stack byte. The mctp_i2c_slave_cb handler leaves the output byte unset for I2C read-request and read-processed events, so Aspeed and NPCM bus drivers return the prior stack byte instead of 0xff. Exploitation requires local access to an exposed mctp-i2c slave device on an affected controller; each read reveals one byte and does not alter kernel state.

CVSS severity5.5
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in the Linux Kernel MCTP-over-I2C driver allows local users to read an uninitialized kernel stack byte. The mctp_i2c_slave_cb handler leaves the output byte unset for I2C read-request and read-processed events, so Aspeed and NPCM bus drivers return the prior stack byte instead of 0xff. Exploitation requires local access to an exposed mctp-i2c slave device on an affected controller; each read reveals one byte and does not alter kernel state.

The record

CVE
CVE-2026-45865
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=5.18
  2. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <11f83253244060b5de5eac787f61ae3f3e559d01
  3. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <1eeedb310229bfee9dd4d992e5bba33fe1378a8f
  4. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <2a14e91b6d76639dac70ea170f4384c1ee3cb48d
  5. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <6ff2ebfef75fbc57d937d8fbe738b967edf2d331
  6. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <93e01e837e105299f1c259ef71f6e1ec4fe806e3
  7. Affected versionversion=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <fa9861e5c8af7651dddfa8d490aaada17ae33b6c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.18; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <11f83253244060b5de5eac787f61ae3f3e559d01; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <1eeedb310229bfee9dd4d992e5bba33fe1378a8f; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <2a14e91b6d76639dac70ea170f4384c1ee3cb48d; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <6ff2ebfef75fbc57d937d8fbe738b967edf2d331; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <93e01e837e105299f1c259ef71f6e1ec4fe806e3; version=f5b8abf9fc3dacd7529d363e26fe8230935d65f8 <fa9861e5c8af7651dddfa8d490aaada17ae33b6c

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0SUSECVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
3.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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