CVE-2026-43221

Incorrect byte return via uninitialized IPMB response

Published May 6, 2026 · Updated May 6, 2026

Use of an uninitialized resource in affected Linux kernel releases allows local users to receive an uninitialized byte through an I2C read. The ipmi_ipmb_slave_cb handler leaves *val unset for I2C_SLAVE_READ_REQUESTED and I2C_SLAVE_READ_PROCESSED, so the bus driver returns stale byte data instead of 0xff. Reachability requires an instantiated IPMI IPMB slave interface; upstream reports only an incorrect byte response, not a crash or service interruption.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of an uninitialized resource in affected Linux kernel releases allows local users to receive an uninitialized byte through an I2C read. The ipmi_ipmb_slave_cb handler leaves *val unset for I2C_SLAVE_READ_REQUESTED and I2C_SLAVE_READ_PROCESSED, so the bus driver returns stale byte data instead of 0xff. Reachability requires an instantiated IPMI IPMB slave interface; upstream reports only an incorrect byte response, not a crash or service interruption.

The record

CVE
CVE-2026-43221
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-908
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 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=5.16
  2. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <102712417bb6aa9a00d852bc59cb0a276db486c4
  3. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <2dfbc8c17dd161885336e77e71c336cd62cf6748
  4. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <56d5c0557e53c4d8d92a619fa83eaae178165e07
  5. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <905554ebd76aeee370bfd5136ea11e0b9d75c6f1
  6. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <9f235ccecd03c436cb1683eac16b12f119e54aa9
  7. Affected versionversion=63c4eb347164845b380089012fe43992511c0ad3 <f726b3a57e00bb6249c67714c11ae8b4b31719a1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.16; version=63c4eb347164845b380089012fe43992511c0ad3 <102712417bb6aa9a00d852bc59cb0a276db486c4; version=63c4eb347164845b380089012fe43992511c0ad3 <2dfbc8c17dd161885336e77e71c336cd62cf6748; version=63c4eb347164845b380089012fe43992511c0ad3 <56d5c0557e53c4d8d92a619fa83eaae178165e07; version=63c4eb347164845b380089012fe43992511c0ad3 <905554ebd76aeee370bfd5136ea11e0b9d75c6f1; version=63c4eb347164845b380089012fe43992511c0ad3 <9f235ccecd03c436cb1683eac16b12f119e54aa9; version=63c4eb347164845b380089012fe43992511c0ad3 <f726b3a57e00bb6249c67714c11ae8b4b31719a1

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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

CWE-908Use of Uninitialized Resource

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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