CVE-2021-38996

Local service interruption via undisclosed CAA kernel flaw

Published Mar 2, 2022 · Updated Sep 17, 2024

Denial of service in IBM AIX 7.1 through 7.3 and PowerVM VIOS 3.1 allows local users to interrupt the host through the AIX kernel. The affected CAA code is delivered in the bos.cluster.rte fileset, but IBM has not disclosed the erroneous kernel operation or triggering input. A non-privileged local account is sufficient; the effect is limited to availability, and IBM does not specify whether interruption means a hang, crash, or reboot.

CVSS severity6.2
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in IBM AIX 7.1 through 7.3 and PowerVM VIOS 3.1 allows local users to interrupt the host through the AIX kernel. The affected CAA code is delivered in the bos.cluster.rte fileset, but IBM has not disclosed the erroneous kernel operation or triggering input. A non-privileged local account is sufficient; the effect is limited to availability, and IBM does not specify whether interruption means a hang, crash, or reboot.

The record

CVE
CVE-2021-38996
Published
Mar 2, 2022
Updated
Sep 17, 2024
Vendor
IBM
Product
AIX
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 2, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record 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=7.1
  2. Affected versionversion=7.2
  3. Affected versionversion=7.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

IBM · AIXversion=7.1; version=7.2; version=7.3
IBM · PowerVM Virtual I/O Serverversion=3.1

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P
6.2IBM CorporationCVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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

T1499Endpoint Denial of Service

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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