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IBM PowerVM Hypervisor CVE-2026-18870

| EUVDEUVD-2026-86006 MEDIUM
Out-of-bounds Read (CWE-125)
2026-09-24 ibm GHSA-468w-j8gw-m9h2
4.3
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Gain adjacent-network position to Power server
  2. Exploit
    Send crafted request to hypervisor interface
  3. Execution
    Trigger out-of-bounds read
  4. Impact
    Receive leaked sensitive memory contents

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires the attacker to be on the same adjacent network segment as the affected IBM PowerVM Hypervisor (AV:A limits reach - not routable/internet-wide exploitation) and to reach a hypervisor firmware interface that processes the malformed input. No authentication (PR:N) or user interaction (UI:N) is needed per the vector. Affected firmware is limited to specific service-pack ranges within FW950/FW1060/FW1110/FW1120 on IBM Power servers; systems on patched levels or off these branches are not exposed. Impact is confined to limited information disclosure (C:L) with no code execution, data modification, or DoS.

Impact

This is a genuinely low-priority issue despite being network/adjacent-reachable. The IBM/NVD CVSS 3.1 vector (AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N, base 4.3) describes an unauthenticated adjacent-network attacker triggering an out-of-bounds read in the PowerVM Hypervisor that leaks a limited amount of sensitive memory (C:L) with no integrity or availability impact. There is no EPSS score, no CISA KEV listing, and no public exploit code, so exploitation status is: no public exploit identified at time of analysis. The only aggravating signals are the low attack complexity and lack of required privileges; the mitigating signals are adjacent-only reach (AV:A, not full internet-facing AV:N), low-only confidentiality impact, and the fact that hypervisor firmware attack surface is not typically exposed to arbitrary attackers. Notably, this CVE's vector differs from sibling PowerVM firmware CVEs (CVE-2026-17504/17503) which were AV:L/PR:H - here it is adjacent and unauthenticated, which is worth verifying against IBM's advisory since hypervisor-level unauthenticated adjacent access is unusual. Net: a real but minor information-leak flaw, not an urgent priority.

Exploit ScenarioDerived

An attacker positioned on the same adjacent network segment as a PowerVM-managed IBM Power server sends a crafted request to a hypervisor-exposed interface, triggering an out-of-bounds read that returns adjacent memory contents. The disclosed bytes could contain limited sensitive firmware state. No public proof-of-concept exists, and the leak is bounded (C:L), so this would most likely serve as a reconnaissance aid rather than a standalone compromise.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 24, 2026

Limited information disclosure affects IBM PowerVM Hypervisor firmware on specific service-pack levels (FW1120.00-FW1120.01, FW1110.00-FW1110.31, FW1060.00-FW1060.81, and FW950.00-FW950.H3), where an out-of-bounds read can expose a small amount of adjacent memory content to an attacker. Rated CVSS 4.3 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N), the flaw requires no authentication or user interaction but is not reachable across the internet: the attacker must already sit on the same adjacent network segment and be able to reach a hypervisor firmware interface that processes malformed input. Impact is confined to partial confidentiality loss with no integrity or availability effect, and no public exploit identified at time of analysis; IBM has published a vendor fix advisory.

RemediationAI

Patch available per vendor advisory: IBM has published a fix for this issue at https://www.ibm.com/support/pages/node/7289135, and the remediation is to upgrade PowerVM hypervisor firmware to the corrected service pack on each affected branch (FW950, FW1060, FW1110, FW1120). The data reviewed does not state the specific corrected build numbers, so confirm the target fix level on IBM's advisory before scheduling the update, and treat any system still within the ranges FW1120.00-FW1120.01, FW1110.00-FW1110.31, FW1060.00-FW1060.81, or FW950.00-FW950.H3 as exposed. Plan for the operational cost of a firmware update, which typically requires a managed-system reboot or at minimum a planned maintenance window, and validate LPAR availability expectations before applying it. Where immediate patching is not possible, the only meaningful compensating controls target the AV:A precondition rather than the coding flaw: isolate the hypervisor management and firmware interfaces on a dedicated, tightly ACL-filtered VLAN and block adjacent-segment access from general-purpose user and workload networks, accepting that this reduces reach but does not eliminate the out-of-bounds read, plus monitor firmware and management-plane logs for unexpected interface traffic. Restricting segments can break legitimate administrative tooling and out-of-band management paths, so stage and test ACL changes before enforcing them.

Affected VersionsENISA

PowerVM Hypervisor FW1110.00 ≤FW1110.31
PowerVM Hypervisor FW1060.00 ≤FW1060.81
PowerVM Hypervisor FW950.00 ≤FW950.H3
PowerVM Hypervisor FW1120.00 ≤FW1120.01

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

PowerVM is the firmware/hypervisor layer that partitions IBM Power servers into LPARs and mediates access to hardware resources, so the vulnerable component is vendor firmware rather than a user-space service. The root cause class is CWE-125 (out-of-bounds read): malformed input accepted by a firmware interface causes the parser to read beyond the bounds of an allocated buffer, returning adjacent memory contents to the caller rather than a bounded, intended value. Because the CVSS vector is AV:A with PR:N and UI:N, exploitation does not require credentials or victim interaction, but it is bounded by network proximity - the attacker must share an adjacent/L2 segment with the affected system and be able to reach the specific firmware interface that handles the input. The vector also shows S:U, C:L, I:N, A:N, meaning the disclosure stays within the hypervisor's security scope and is limited in volume, with no demonstrated path to code execution, privilege escalation, or denial of service. The CPE string cpe:2.3:a:ibm:powervm_hypervisor:*:*:*:*:*:*:*:* is a vendor-scoped wildcard that does not by itself enumerate patched versus unpatched builds, so version applicability must be resolved against the firmware branch ranges in IBM's advisory.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (ibm) PRIMARY MEDIUM
NVD 4.3 MEDIUM
AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
vuln.today AI 4.3 MEDIUM

Agree with IBM: adjacent reach for a hypervisor firmware interface (AV:A), no auth or interaction, and an OOB read yielding only limited sensitive data (C:L, I:N, A:N).

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (ibm).

CVSS VectorNVD

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

DescriptionNVD

IBM PowerVM Hypervisor FW1120.00 through FW1120.01, FW1110.00 through FW1110.31, FW1060.00 through FW1060.81, and FW950.00 through FW950.H3 could allow a remote attacker to obtain sensitive information due to an out-of-bounds read.

Threat Intelligence Overview

EPSS Score
0.2%
Top 93% exploitable
Prevalence
Low
enterprise IBM Power Systems virtualization firmware, industry-specific footprint
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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