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IBM i EUVDEUVD-2026-57377

| CVE-2026-16856 HIGH
OS Command Injection (CWE-78)
2026-08-12 ibm GHSA-67x9-wvm5-8cxw
8.8
CVSS 3.1 · Vendor: ibm
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Attack ChainAIDerived

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

  1. Access
    Obtain low-privilege IBM i user account
  2. Delivery
    Identify vulnerable OS command interface accepting user input
  3. Exploit
    Craft input containing shell metacharacters to inject secondary command
  4. Execution
    Submit crafted input to trigger unsanitized OS command execution
  5. Persist
    Execute arbitrary OS command under vulnerable program context
  6. Impact
    Escalate to *ALLOBJ or SYSADM authority for full system control

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization OS command sanitization, avoid shell exec
MITRE ATT&CK

2 techniques across 1 tactic: Execution

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

Exploitation Conditions

A valid IBM i user account with at least low-level privileges is required - the CVSS PR:L metric confirms unauthenticated exploitation is not possible. The NVD-assigned vector lists AV:N, but the description explicitly states 'local attacker,' creating a conflict: if AV:L is accurate, the attacker must have an active local session (e.g., interactive 5250 terminal, SSH, or equivalent local access) on an affected IBM i 7.5 or 7.6 system. No specific non-default configuration, enabled feature, or particular service is identified in the available data as a prerequisite beyond possession of a valid user account on an affected version. The key limiting factor is local access: if AV:L applies, remote internet-based attackers without an existing foothold cannot directly exploit this vulnerability.

Impact

A significant and unresolved discrepancy exists between the NVD-assigned CVSS vector (AV:N, implying network-exploitable) and the description's explicit characterization of a 'local attacker' - security teams should verify the true attack vector directly against the IBM advisory at https://www.ibm.com/support/pages/node/7283284 before drawing firm conclusions about exploitability scope. If AV:L is correct, the attack surface is substantially narrower than the 8.8 score implies, requiring physical or authenticated local session access. The PR:L metric is consistent with the 'local attacker' framing and confirms at least a low-privilege account is required. No EPSS data was supplied, there is no CISA KEV listing, and no public exploit code exists, all of which reduce emergency patching urgency relative to a publicly weaponized flaw - but the C:H/I:H/A:H impact triad is unambiguous: successful exploitation yields full IBM i system compromise. Any organization running IBM i 7.5 or 7.6 on Power Systems infrastructure should treat this as a priority remediation item on their next maintenance cycle, particularly given the sensitive workloads - payroll, ERP, core banking - that IBM i environments typically host.

Exploit ScenarioDerived

A local attacker with a standard low-privilege IBM i user profile - such as a developer, operator, or compromised service account - identifies a vulnerable program or system command interface that passes user-controlled input to an OS command without proper sanitization. The attacker submits crafted input containing shell metacharacters to inject a secondary OS command, such as one that modifies their own user profile to grant *ALLOBJ authority or runs a privileged adopted-authority program, gaining full system control. No public proof-of-concept code has been identified, so exploitation currently requires independent discovery of the specific vulnerable code path within IBM i.

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 12, 2026

OS command injection in IBM i 7.5 and 7.6 enables a local attacker holding low-level credentials to escalate privileges to a highly elevated system authority level by injecting shell metacharacters into an unsanitized OS command interface (CWE-78). Both release streams - 7.5 and 7.6 - running on IBM Power Systems hardware are confirmed affected per the IBM advisory. IBM has released a patch via their support portal; no CISA KEV listing and no public exploit code have been identified at time of analysis.

RemediationAI

Apply the vendor-released patch available from IBM's support portal at https://www.ibm.com/support/pages/node/7283284 for IBM i versions 7.5 and 7.6. The input data confirms patch availability but does not specify an exact PTF (Program Temporary Fix) identifier or cumulative package level, so administrators must consult the advisory page directly to retrieve the correct fix package for their release stream. As a compensating control prior to patching, restrict local and remote interactive login access to only explicitly authorized accounts, and audit all user profiles holding *ALLOBJ, *SECADM, or *JOBCTL special authorities to reduce the pool of accounts that could leverage a successful injection. Reviewing IBM i adopted-authority programs (*PGM objects with USRPRF(*OWNER)) and restricting which user profiles may submit batch jobs can further limit the blast radius. Note that restricting general user accounts may have operational impact in 5250-terminal-dependent workflows and should be coordinated with application owners.

Affected VersionsENISA

i 7.5
i 7.6

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 a proprietary integrated operating system that runs exclusively on IBM Power Systems hardware, predominantly deployed in enterprise workloads in the finance, manufacturing, and retail sectors. CWE-78 (Improper Neutralization of Special Elements used in an OS Command) indicates that one or more IBM i components fail to sanitize user-controlled input before passing it to an OS-level command execution interface, allowing injection of shell metacharacters such as semicolons, pipes, or backticks to chain attacker-supplied commands. The CPE string cpe:2.3:a:ibm:i:*:*:*:*:*:*:*:* covers all IBM i version substrings; the advisory explicitly scopes affected releases to 7.5 and 7.6. Successful injection causes arbitrary OS commands to execute in the context of the vulnerable program, potentially under adopted authority granting *ALLOBJ or *SECADM special authority - effectively full system control.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (ibm) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Description specifies 'local attacker,' so AV:L is assessed over the NVD-assigned AV:N; PR:L reflects the required low-privilege account; full C/I/A from privilege escalation to system authority.

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

Primary rating from Vendor (ibm).

CVSS VectorVendor: ibm

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

DescriptionCVE.org

IBM i 7.6, and 7.5 could allow a local attacker to gain elevated privileges due to improper neutralization of special elements used in an OS command.

Executive ViewAI

Why It Matters

IBM i 7.5 and 7.6 systems running on IBM Power Systems contain a privilege escalation vulnerability (CVE-2026-16856) that allows local users with low-level credentials to gain complete system authority, exposing organizations to insider threats and potential compromise of mission-critical business operations. With a CVSS score of 8.8, this vulnerability poses significant risk to any organization operating IBM i infrastructure in production environments.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.3%
Top 73% exploitable
Prevalence
Medium
enterprise IBM Power Systems deployments, significant in finance and manufacturing 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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

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