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IBM i EUVDEUVD-2026-58369

| CVE-2026-16853 HIGH
Out-of-bounds Read (CWE-125)
2026-08-13 ibm GHSA-ghg6-4m36-hf44
7.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Identify internet-exposed IBM i service
  2. Delivery
    Send crafted malformed network request
  3. Exploit
    Trigger out-of-bounds read in vulnerable component
  4. Execution
    Receive leaked sensitive memory contents
  5. Impact
    Optionally cause minor service disruption

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) indicates exploitation requires no authentication, no user interaction, and no elevated privileges - only network connectivity to the affected IBM i system. No specific feature, configuration setting, or non-default deployment mode is identified in the available description as a prerequisite. Exploitation is limited by the scope of the vulnerable component: only IBM i versions 7.3, 7.4, 7.5, and 7.6 are affected; IBM i 7.2 and earlier, and any future release not listed, are not confirmed vulnerable based on available data. The impact is bounded to partial confidentiality loss (C:L) and minor availability disruption (A:L); full system compromise or code execution is not indicated by the CWE-125 classification or CVSS metrics.

Impact

The CVSS base score of 6.5 (Medium) reflects a moderate but real risk profile. The attack vector is Network (AV:N), complexity is Low (AC:L), and no privileges or user interaction are required (PR:N/UI:N), making this a low-friction, unauthenticated network-exploitable flaw - a meaningful threat in any internet-exposed or intranet-accessible IBM i deployment. Impact is limited: C:L indicates partial confidentiality loss (sensitive memory contents, not full system compromise), I:N confirms no integrity impact, and A:L suggests a minor availability disruption is possible. No EPSS score was provided in the input data, so exploitation probability cannot be quantified. The vulnerability is not listed in the CISA KEV catalog and no public proof-of-concept exploit has been identified, suggesting no confirmed widespread active exploitation at time of analysis. Despite the medium CVSS score, the unauthenticated network vector elevates practical priority for externally-reachable IBM i systems. The absence of KEV listing is a moderating factor, but the low attack complexity warrants prompt patching rather than deferral.

Exploit ScenarioDerived

An unauthenticated remote attacker sends a specially crafted network request to a vulnerable IBM i 7.3-7.6 system targeting a network-accessible service affected by the out-of-bounds read flaw. The malformed input causes the service to read beyond its allocated buffer, returning fragments of sensitive memory contents - potentially including credentials, session tokens, or application data - to the attacker. The same request may also trigger a minor service disruption consistent with the A:L impact metric. No public exploit code has been identified, but the low attack complexity (AC:L) means a functional exploit would not require significant sophistication to develop.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 13, 2026

Out-of-bounds read in IBM i 7.3 through 7.6 exposes sensitive memory contents to unauthenticated remote attackers over the network, with additional limited availability impact. The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U) confirms exploitation requires no authentication and no user interaction, lowering the barrier for opportunistic targeting. No public exploit code or CISA KEV listing has been identified at time of analysis, though a vendor patch is available.

RemediationAI

Apply the vendor-released patch as documented in IBM's support advisory at https://www.ibm.com/support/pages/node/7283573. IBM i updates are distributed as PTFs (Program Temporary Fixes); administrators should identify the specific PTF number for their installed release (7.3, 7.4, 7.5, or 7.6) from the advisory and apply it through the standard IBM i PTF management process. An exact fixed version number was not independently extractable from the provided data - consult the IBM advisory directly to confirm the correct PTF for each release level. As a compensating control prior to patching, restricting network-level access to IBM i services via firewall rules or IBM i host table access controls can reduce exposure, though this does not eliminate the underlying flaw and may impact legitimate business operations. IBM i systems should not be directly internet-exposed as a baseline security posture.

Affected VersionsENISA

i 7.5
i 7.4
i 7.6
i 7.3

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 AS/400 and iSeries) is IBM's integrated operating system and middleware stack running on IBM Power Systems servers, widely used in enterprise environments for mission-critical workloads. The root cause is CWE-125 (Out-of-bounds Read), a memory safety flaw where a component reads data beyond the allocated buffer boundary. This class of vulnerability in a network-accessible component can expose adjacent memory regions containing sensitive data such as credentials, keys, or business data. The tags include 'Buffer Overflow,' which may reflect the broader vulnerability family rather than a distinct write condition - the authoritative CWE-125 classification identifies this specifically as a read overrun. The CPE cpe:2.3:a:ibm:i:*:*:*:*:*:*:*:* covers all sub-versions of IBM i, consistent with the vendor's statement of affected releases 7.3, 7.4, 7.5, and 7.6.

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Severity by source

Vendor (ibm) PRIMARY MEDIUM
NVD 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 6.5 MEDIUM

Network-exploitable unauthenticated read overrun; limited confidentiality and availability impact, no integrity or scope change.

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

Primary rating from Vendor (ibm).

CVSS VectorNVD

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

Lifecycle Timeline

2
Severity Changed
Aug 17, 2026 - 17:22 NVD
MEDIUM HIGH
CVSS changed
Aug 17, 2026 - 17:22 NVD
6.5 (MEDIUM) 7.5 (HIGH)

DescriptionNVD

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to obtain sensitive information due to an out-of-bounds read.

Threat Intelligence Overview

EPSS Score
0.3%
Top 74% exploitable
Prevalence
Medium
enterprise IBM Power platform, dominant in banking and insurance verticals
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 HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
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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