Power System Integer Overflow

Answer in brief

CVE-2026-16661 records a Unknown severity vulnerability in Power System Integer Overflow. The current sources do not mark it as known exploited. The current feed maps IBM/PowerVM Hypervisor (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 19, 2026Updated Aug 19, 2026Source checked Aug 19, 2026First seen by HOL Aug 19, 2026Material review Aug 19, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps IBM/PowerVM Hypervisor (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
IBM/PowerVM Hypervisorgeneric	FW1120.00 \|\| FW1110.00 \|\| FW1060.00 \|\| FW950.00	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for IBM/PowerVM Hypervisor.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 19, 2026

Sources and claim methodology

Source referenceibm.com

Upstream source description

IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2 is affected by a vulnerability in the service processor mailbox interface. An attacker with authenticated service-level access to the FSP can exploit this vulnerability, allowing arbitrary code to be executed in the host firmware runtime, giving full control over the managed system, resulting in a confidentiality, integrity, and availability impact to the managed system.

Quoted source text, attributed separately from HOL analysis.