CVE-2026-16855: Vulnerabilities in IBM AIX and PowerVM VIOS

Q: What access does an attacker need to exploit this issue?

The issue is described as locally exploitable, so the attacker needs local access to an affected IBM AIX or IBM PowerVM VIOS system.

Q: Which systems should be considered exposed?

Systems running IBM AIX or IBM PowerVM VIOS should be assessed, particularly where untrusted or less-trusted users can obtain local access.

Published Aug 15, 2026

Updated

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to cause a denial of service due to a heap buffer overflow.

Affected Software

10 affected components

IBM AIX<=7.2

IBM AIX<=7.3

IBM PowerVM VIOS<=4.1

IBM AIX>=7.2.5<=7.2.5.212

IBM AIX>=7.3.2<=7.3.2.5

IBM AIX>=7.3.3<=7.3.3.2

IBM AIX>=7.3.4<=7.3.4.1

IBM VIOS>=4.1.0<4.1.0.50

IBM VIOS>=4.1.1.0<4.1.1.30

IBM VIOS>=4.1.2.0<4.1.2.20

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade IBM AIX 7.2 / 7.3 to a version that resolves this vulnerability.
Fixed in SP13
Upgrade
Upgrade IBM PowerVM VIOS 4.1 to a version that resolves this vulnerability.
Fixed in 4.1.1.30
Upgrade
Upgrade IBM PowerVM VIOS 4.1 to a version that resolves this vulnerability.
Fixed in 4.1.0.50
Upgrade
Upgrade IBM PowerVM VIOS 4.1 to a version that resolves this vulnerability.
Fixed in 4.1.2.20
Compensating control
After applying the AIX service pack / VIOS fix pack updates, reboot the LPAR to complete the SP/FP update (LPAR reboot is required).

Event History

Aug 15, 2026

CVE Published

via IBM·12:00 AM

Data Sourced

via IBM·12:00 AM

DescriptionAffected Software

Aug 19, 2026

CVE Published

via MITRE·07:38 PM

Data Sourced

via MITRE·07:38 PM

RemedyDescriptionSeverityWeakness

Data Sourced

via NVD·08:17 PM

RemedyDescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

IBM-7283858

Frequently Asked Questions

What access does an attacker need to exploit this issue?

The issue is described as locally exploitable, so the attacker needs local access to an affected IBM AIX or IBM PowerVM VIOS system.

Which systems should be considered exposed?

Systems running IBM AIX or IBM PowerVM VIOS should be assessed, particularly where untrusted or less-trusted users can obtain local access.

CVE-2026-16855: Vulnerabilities in IBM AIX and PowerVM VIOS

Affected Software

Remediation

Event History

Parent advisories

Frequently Asked Questions

What access does an attacker need to exploit this issue?

Which systems should be considered exposed?

Company

Resources

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