IBM i CVE-2026-18715

Exploitation requires a valid authenticated account on the affected IBM i system with at least low-privileged access (confirmed by CVSS PR:L). The attacker must be able to submit XML input to a component of IBM i that processes XML with external entity resolution enabled. The CVE description does not reference any special non-default configuration as a prerequisite beyond authenticated access to the XML-processing interface. Limiting factors include the mandatory authentication requirement, which restricts exploitation to credentialed insiders, compromised accounts, or scenarios where IBM i authentication has been bypassed by prior compromise. Versions outside the confirmed range of 7.3-7.6 are not listed as affected.

The CVSS 6.5 score is grounded in a network-accessible, low-complexity attack (AV:N/AC:L) requiring only low-privileged authentication (PR:L), yielding high confidentiality impact (C:H) with no integrity or availability consequence (I:N/A:N/S:U). The PR:L requirement meaningfully narrows the real-world attack surface compared to unauthenticated flaws - exploitation is limited to users with valid IBM i credentials. No EPSS score was provided in the available data, no KEV listing exists, and no public POC has been identified at time of analysis, all of which suggest limited opportunistic exploitation risk at present. The primary concern is insider threat or post-compromise lateral movement scenarios where an attacker has already obtained a low-privileged IBM i account. The moderate CVSS score reflects genuine but constrained risk rather than a critical, widely-exploitable exposure.

An attacker with a valid low-privileged IBM i user account submits a crafted XML document containing an external entity declaration (e.g., pointing to a sensitive local file such as a system password store or configuration file) to an XML-processing endpoint on the IBM i platform. The parser resolves the external entity without restriction and reflects the file contents back in the response, exposing sensitive system information to the attacker. No public POC has been identified at time of analysis.