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IBM i CVE-2026-17057

| EUVDEUVD-2026-71482 CRITICAL
Missing Authentication for Critical Function (CWE-306)
2026-09-04 ibm GHSA-48hc-r2hp-8cx3
Critical
Disputed · 9.1 NVD
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Attack ChainAIDerived

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

  1. Access
    Reach exposed IBM i service over network
  2. Delivery
    Invoke critical function without authentication
  3. Exploit
    Bypass absent auth check (CWE-306)
  4. Execution
    Trigger DoS or unauthorized data modification
  5. Impact
    Business disruption and integrity loss

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication required for critical functions
MITRE ATT&CK

1 technique across 1 tactic: Initial Access

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

Exploitation Conditions

Exploitation requires only network reachability to the vulnerable IBM i service exposing the critical function - no authentication, no user interaction, and no non-default configuration are indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). No special conditions beyond reaching the affected service on IBM i 7.3-7.6. The primary limiting factor is network exposure: environments that segment IBM i management/service ports away from untrusted networks materially reduce reachability, and the impact is confined to integrity and availability (no confidentiality loss per C:N).

Impact

The CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H (9.1 Critical) describes a low-complexity, remote, unauthenticated attack with high integrity and availability impact but no confidentiality exposure - internally consistent with a missing-authentication DoS/tamper flaw. However, the signals diverge on urgency: EPSS is only 0.36% (29th percentile) and the CVE is not in CISA KEV, so despite the high base score there is no evidence of active or imminent mass exploitation. There is no public POC identified. In practice this is a high-severity issue that should be patched on IBM i's normal risk cadence but does not currently show the exploitation velocity of a drop-everything emergency. Note the SSVC/automatable and detailed technical-impact fields are not provided in the input, so exploitability nuance beyond CVSS could not be fully assessed.

Exploit ScenarioDerived

An attacker with network reach to an exposed IBM i system sends a request directly to the affected critical function, which processes it without ever requiring authentication. The attacker either forces the service into a denial-of-service condition or alters data/state it controls, disrupting business operations without needing any valid credentials; no public POC is currently known.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv2 – Sep 08, 2026

Remote denial of service and data integrity compromise in IBM i (formerly OS/400) releases 7.3, 7.4, 7.5, and 7.6 stems from a critical function that ships without an authentication check (CWE-306), letting a network attacker invoke it without credentials. IBM has released a fix, and no public exploit has been identified at time of analysis; EPSS is low at 0.36% (29th percentile), indicating no observed exploitation pressure yet.

Earlier versions of this analysis (1)
v1 Sep 04, 2026 - 17:39 CVSS 6.5

Unauthenticated remote exploitation of IBM i 7.3 through 7.6 exposes critical functions without authentication checks, enabling network attackers to degrade availability and corrupt data integrity. The root cause is CWE-306 (Missing Authentication for Critical Function), where specific network-accessible functions can be invoked without credentials, directly resulting in denial-of-service conditions and limited data integrity violations. No public exploit code has been identified and the vulnerability is not listed in the CISA KEV catalog; IBM has released a patch via the referenced advisory.

RemediationAI

Apply the IBM-provided fix per the vendor bulletin at https://www.ibm.com/support/pages/node/7285847 (Patch available per vendor advisory), which supplies PTFs/Group PTF updates for the supported IBM i 7.3, 7.4, 7.5, and 7.6 releases - apply the correct PTF level for your installed release. The input does not include a discrete fix build string, so use the exact PTF identifiers listed in that bulletin rather than an inferred version. As a compensating control until the PTF is loaded, restrict network reachability to the affected IBM i service by firewalling or ACL-limiting access to trusted management hosts/subnets only; the trade-off is that legitimate remote clients of that function will also be blocked, so validate which ports/services the bulletin identifies before restricting. Because the flaw affects integrity and availability, also increase monitoring and back up critical libraries so tampering or a DoS event can be detected and recovered.

Affected VersionsENISA

i 7.4
i 7.5
i 7.3
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 is IBM's integrated midrange operating system running on Power Systems hardware, widely used for business-critical ERP, banking, and manufacturing workloads. The root cause is CWE-306 (Missing Authentication for a Critical Function): a network-reachable function that performs a security-relevant operation does not verify the caller's identity before acting. The affected component is identified by CPE cpe:2.3:a:ibm:i across all supported releases (7.3 through 7.6). Because the missing check is on the function itself rather than a bypassable auth layer, any party able to reach the service endpoint can drive it, producing both availability loss and unauthorized state changes.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Sources disagree (Medium–Critical)
Vendor (ibm) PRIMARY MEDIUM
NVD 9.1 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
vuln.today AI 9.1 CRITICAL

Missing authentication makes it network-reachable and unauthenticated (AV:N/AC:L/PR:N/UI:N); impact is integrity and availability with no confidentiality exposure (C:N/I:H/A:H).

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

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorNVD

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

Lifecycle Timeline

3
Analysis Updated
Sep 08, 2026 - 17:28 vuln.today
v2 - CVSS changed
Severity Changed
Sep 08, 2026 - 17:22 NVD
MEDIUM CRITICAL
CVSS changed
Sep 08, 2026 - 17:22 NVD
6.5 (MEDIUM) 9.1 (CRITICAL)

DescriptionNVD

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service and affect data integrity due to missing authentication for critical functions.

Executive ViewAI

Why It Matters

IBM i operating system versions 7.3 through 7.6 contain a critical unauthenticated vulnerability enabling remote attackers to disrupt business operations and compromise data integrity without valid credentials. Organizations running IBM i should immediately assess exposure and prioritize patching to eliminate risk of network-based service disruptions and data corruption affecting mission-critical systems.

Business Impact: Severe
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.4%
Top 71% exploitable
Prevalence
Medium
IBM i is common in enterprise midrange/ERP shops but not ubiquitous
Data Quality
4 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 CRITICAL
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
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
Out-of-Cycle
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Very High

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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

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