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IBM Db2 Mirror EUVDEUVD-2026-71602

| CVE-2026-18567 MEDIUM
Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)
2026-09-04 psirt@us.ibm.com GHSA-78r8-68cm-88f6
4.7
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Obtain local OS account on IBM i
  2. Delivery
    Identify predictable socket path in world-writable directory
  3. Exploit
    Pre-create attacker-controlled socket at that path
  4. Execution
    Trigger or wait for Db2 Mirror service (re)start
  5. Persist
    Service connects to attacker socket
  6. Impact
    Intercept IPC data for information disclosure

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture TOCTOU prevention
Exploitation Conditions

Exploitation requires a local OS-level account on the IBM i system running IBM Db2 Mirror for i 7.4, 7.5, or 7.6 with at least *W (write) authority to the world-writable IFS directory containing the socket path. The attacker must act before or concurrently with the Db2 Mirror service binding its socket - most practically, around service startup or restart. Limiting factors: exploitation is confined to local authenticated users; IBM i is not internet-exposed by default; the impact is partial confidentiality loss (C:L) and minor availability disruption (A:L), not full system compromise. No network-facing exploitation path exists based on AV:L.

Impact

The provided CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L) scores 4.4 (Medium). Attack vector is strictly local, and PR:L requires an authenticated OS-level account on the IBM i system - limiting the exploitable population to users with interactive or batch job access. AC:L is somewhat generous for a race condition; however, because the socket path is predictable and the directory is world-writable, an attacker can pre-stage the socket before service startup without precise timing, making the 'race' trivially winnable and AC:L defensible. The C:L impact (partial confidentiality loss) and A:L (minor availability disruption if the service fails to bind) are consistent with socket-hijacking primitives. No KEV listing and no public exploit exist, and EPSS data was not provided. IBM i environments are specialized and not internet-facing by default, further constraining real-world risk. This is a low-urgency finding for most organizations but warrants patching on any IBM i system where local user accounts are not tightly controlled.

Exploit ScenarioDerived

A local attacker with a standard OS user account on the IBM i system identifies the predictable Unix domain socket path used by Db2 Mirror for i before the service starts (e.g., at partition boot or service restart). The attacker pre-creates a socket at that path in the world-writable directory, causing Db2 Mirror to inadvertently connect to the attacker-controlled socket, exposing sensitive IPC data such as replication control messages or configuration information. No public exploit code is known to exist at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 04, 2026

Local information disclosure in IBM Db2 Mirror for i 7.4, 7.5, and 7.6 stems from a predictable Unix domain socket path placed in a world-writable directory, enabling a TOCTOU race condition (CWE-367). A local, low-privileged attacker can pre-create or replace the socket at the predictable path before the Db2 Mirror service claims it, intercepting communications that flow through that socket and obtaining sensitive information. No active exploitation has been confirmed, and no public exploit code has been identified at time of analysis.

RemediationAI

Apply the fix documented in the IBM support advisory at https://www.ibm.com/support/pages/node/7285904; an exact patched version number was not independently confirmed from the input data. Until a patch is applied, compensating controls include restricting the world-writable directory containing the socket so that only the Db2 Mirror service account and privileged users have write access (e.g., using IBM i object-level authority to limit *PUBLIC from *RWX to *X or less on the relevant IFS directory). Additionally, restricting interactive sign-on access to the IBM i partition to only essential personnel limits the pool of users who could stage the attack. These mitigations reduce but do not eliminate risk if local users retain any filesystem write capability.

Affected VersionsENISA

Db2 Mirror for i 7.5
Db2 Mirror for i 7.6
Db2 Mirror for i 7.4

Affected Packages

euvd db2_mirror_for_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

CWE-367 (Time-of-check Time-of-use Race Condition) arises when an application constructs a resource path that is both predictable and located in a directory writable by untrusted users. On Unix-like systems, placing a Unix domain socket in /tmp or another world-writable directory allows any local user to pre-create a socket (or symlink) at the expected path before the legitimate service does. When the service attempts to bind, the attacker's socket is already present, enabling interception of IPC traffic. IBM Db2 Mirror for i is a high-availability replication component running on IBM i (AS/400) systems; affected versions are 7.4, 7.5, and 7.6 per the vendor advisory at https://www.ibm.com/support/pages/node/7285904. No CPE string was provided in the input, so version identification relies solely on the IBM advisory.

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Severity by source

NVD PRIMARY 4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 4.4 MEDIUM

Local-only access, low privileges required; predictable path makes race trivially winnable (AC:L); impacts are partial confidentiality and minor availability only.

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

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

1
CVSS changed
Sep 08, 2026 - 21:53 NVD
4.4 (MEDIUM) 4.7 (MEDIUM)

DescriptionNVD

IBM Db2 Mirror for i 7.4, 7.5, and 7.6 could allow a local attacker to obtain information due to a race condition involving a predictable Unix domain socket path in a world-writable directory.

Threat Intelligence Overview

EPSS Score
0.1%
Top 100% exploitable
Prevalence
Low
IBM i (AS/400) is niche, used in specific enterprise 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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
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
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

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

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