Skip to main content

IBM i EUVDEUVD-2026-58462

| CVE-2026-18020 MEDIUM
Out-of-bounds Read (CWE-125)
2026-08-13 ibm GHSA-mvj4-44w4-mc7c
5.3
CVSS 3.1 · Vendor: ibm
View

Attack ChainAIDerived

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

  1. Access
    Identify network-reachable IBM i instance
  2. Delivery
    Send crafted network request to vulnerable service
  3. Exploit
    Trigger off-by-one bounds error in parsing logic
  4. Execution
    Out-of-bounds read faults targeted component
  5. Persist
    Service crashes or hangs
  6. Impact
    Availability disrupted for dependent users

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

The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U) indicates no special prerequisites beyond network-level access to the IBM i system: no authentication, no user interaction, and no non-default configuration is required to trigger the vulnerability. Any IBM i 7.3, 7.4, 7.5, or 7.6 instance reachable over the network to an attacker is potentially exploitable in its default state. Exploitation is bounded in impact to partial availability disruption (A:L) - the confirmed outcome is a denial-of-service crash or hang in the affected component, not full system takeover or data exfiltration. The 'Information Disclosure' tag in source metadata conflicts with the CVSS C:N rating; if the out-of-bounds read does expose buffer contents to the attacker, the actual exploitation conditions may enable a secondary information exposure not reflected in the current score - IBM's advisory should be consulted to resolve this discrepancy.

Impact

The CVSS 3.1 base score of 5.3 (Medium) accurately reflects the constrained impact profile: the attack vector is network (AV:N), complexity is low (AC:L), no authentication or user interaction is required (PR:N/UI:N/S:U), but the availability impact is only partial (A:L) with zero confidentiality or integrity effect. No EPSS probability data was supplied, and this CVE does not appear in the CISA KEV catalog, meaning no confirmed active exploitation has been reported. The absence of public proof-of-concept code further tempers urgency. The conflicting 'Information Disclosure' tag versus the CVSS C:N metric is a data quality concern - even a mid-sized municipal IT team in gdynia running IBM i for payroll or ERP processing should verify with IBM whether any bounded read data is surfaced to the attacker before concluding the impact is purely DoS. Overall, this is a genuine but bounded risk: trivially reachable with no prerequisites, but limited to partial service disruption rather than system compromise or data theft, placing it appropriately at medium priority behind critical and high findings.

Exploit ScenarioDerived

An unauthenticated remote attacker sends a specially crafted network request to a vulnerable IBM i system, supplying input calculated to trigger the off-by-one bounds error in the affected parsing or processing component. The resulting out-of-bounds read causes the targeted service to fault and become unresponsive, creating a denial-of-service condition for users dependent on that IBM i resource. No public proof-of-concept code has been identified at time of analysis, so exploitation currently requires independent rediscovery of the triggering input.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Aug 13, 2026

Denial-of-service exposure in IBM i versions 7.3 through 7.6 enables unauthenticated remote attackers to disrupt availability via an off-by-one error in bounds checking logic (CWE-125). The CVSS vector confirms network-accessible, low-complexity, unauthenticated exploitation with limited availability impact and no confirmed confidentiality or integrity effects, though the 'Information Disclosure' tag present in source metadata creates a discrepancy worth verifying with IBM. No public exploit has been identified at time of analysis, and IBM has issued a patch through its support portal.

RemediationAI

IBM has released a patch addressing this vulnerability, accessible through the IBM support portal at https://www.ibm.com/support/pages/node/7283573. Organizations running IBM i 7.3, 7.4, 7.5, or 7.6 should apply the vendor-supplied PTF as the primary remediation. An exact patched PTF number or release version was not specified in the available reference data - consult the IBM advisory directly for fix-level details before scheduling maintenance windows. As a compensating control prior to patching, administrators should consider restricting network access to IBM i service endpoints at the perimeter firewall to known and trusted IP ranges; note this may limit legitimate remote access and should be balanced against operational requirements. IBM i environments that expose services publicly without filtering face the highest residual risk until the fix is applied.

Affected VersionsENISA

i 7.3
i 7.5
i 7.6
i 7.4

Affected Packages

euvd i no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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

Technical ContextAI · show details

IBM i (formerly OS/400 and i5/OS) is IBM's proprietary integrated operating system for Power Systems hardware, commonly deployed in banking, insurance, manufacturing, and government for mission-critical transactional workloads. The root cause is CWE-125 (Out-of-bounds Read), arising from an off-by-one error in bounds-checking logic - a class of defect where a loop or index calculation reads one element beyond a buffer's valid boundary. This can cause crashes in the affected component when the overread triggers a fault, producing the observed denial-of-service outcome. The CPE string cpe:2.3:a:ibm:i:*:*:*:*:*:*:*:* covers all editions and patch levels of IBM i across the confirmed affected release lines. Notably, the source tags reference 'Buffer Overflow' and 'Information Disclosure,' but CWE-125 is an out-of-bounds read rather than a write overflow, and the CVSS impact metrics assign C:N, making information disclosure unconfirmed from the authoritative scoring.

Know when the next one hits your stack

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources

No credit card · 7-day full trial

Severity by source

Vendor (ibm) PRIMARY 5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
vuln.today AI 5.3 MEDIUM

Network-reachable unauthenticated DoS with no authentication barrier; availability impact limited to partial; no confidentiality or integrity impact supported by description.

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

Primary rating from Vendor (ibm).

CVSS VectorVendor: ibm

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

DescriptionCVE.org

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service due to an off-by-one error in bounds checking.

Threat Intelligence Overview

EPSS Score
0.3%
Top 79% exploitable
Prevalence
Medium
enterprise IBM Power Systems OS, prevalent in banking, insurance, and manufacturing
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 0.3%
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
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
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.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy