CVE-2026-17156: IBM App Connect Enterprise RCE Vulnerability

CVE-2026-17156 Overview

CVE-2026-17156 is an insecure deserialization vulnerability [CWE-502] in IBM App Connect Enterprise. The flaw affects versions 13.0.1.0 through 13.0.8.0 and 12.0.1.0 through 12.0.12.27. A local attacker can leverage the flaw to execute arbitrary code on affected systems. Successful exploitation requires user interaction and yields full impact on confidentiality, integrity, and availability of the host.

Critical Impact
Local attackers can achieve arbitrary code execution on IBM App Connect Enterprise hosts by supplying crafted serialized data, compromising integration workflows and connected enterprise systems.

Affected Products

IBM App Connect Enterprise 13.0.1.0 through 13.0.8.0
IBM App Connect Enterprise 12.0.1.0 through 12.0.12.27
Integration servers and flows dependent on the affected runtime

Discovery Timeline

2026-09-14 - CVE-2026-17156 published to the National Vulnerability Database (NVD)
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-17156

Vulnerability Analysis

The vulnerability stems from unsafe handling of serialized objects within IBM App Connect Enterprise. When the runtime deserializes attacker-controlled data, it instantiates objects without validating type or content. This behavior allows a local attacker to craft a malicious serialized payload that triggers code execution during deserialization.

Exploitation requires local access to the host and user interaction to process the malicious input. The attack does not require prior authentication, but the payload must reach a deserialization sink within the App Connect runtime. Successful exploitation runs code in the context of the App Connect Enterprise process, which typically holds broad access to integration endpoints and credentials.

The EPSS score is 0.141% with a percentile of 3.81, indicating low observed exploitation activity at publication.

Root Cause

The root cause is insecure deserialization [CWE-502]. IBM App Connect Enterprise deserializes untrusted input without enforcing type restrictions or integrity checks. Java-based deserialization sinks in the affected releases accept crafted object graphs that trigger gadget chains during reconstruction.

Attack Vector

The attack vector is local. An attacker with access to the host, or the ability to place a crafted file where the runtime processes it, submits a malicious serialized object. When a user or process handles the input, the runtime deserializes the payload and executes attacker-controlled logic. Refer to the IBM Support Page for vendor technical details.

Detection Methods for CVE-2026-17156

Indicators of Compromise

Unexpected child processes spawned by the App Connect Enterprise runtime (IntegrationServer, DataFlowEngine)
New or modified serialized object files (.ser, .bin) staged in integration input directories
Outbound network connections from integration server processes to unfamiliar hosts
Java stack traces referencing ObjectInputStream.readObject tied to unusual class loads

Detection Strategies

Monitor App Connect Enterprise process trees for anomalous command execution following message processing
Inspect integration server logs for deserialization errors, class-not-found exceptions, or unexpected class loads
Apply behavioral analytics to flag integration runtimes writing to disk locations outside normal working directories

Monitoring Recommendations

Enable verbose audit logging on integration flows that accept serialized payloads
Forward host and application telemetry to a centralized SIEM for correlation across integration nodes
Alert on file creation events for serialized object extensions in message queue and file input directories

How to Mitigate CVE-2026-17156

Immediate Actions Required

Upgrade IBM App Connect Enterprise to a fixed release above 13.0.8.0 for the 13.x branch or above 12.0.12.27 for the 12.x branch
Restrict local access to App Connect Enterprise hosts and integration server working directories
Audit integration flows that consume serialized Java objects and disable those not required

Patch Information

IBM has published remediation guidance on the IBM Support Page. Apply the vendor-supplied fix pack or interim fix for the affected release. Validate the runtime version after upgrade to confirm the patched build is active.

Workarounds

Remove or disable integration nodes that deserialize untrusted Java objects until the patch is applied
Enforce least-privilege permissions on directories monitored by file input nodes
Apply operating system access controls to limit which users can place files in integration input paths

bash

# Verify installed IBM App Connect Enterprise version
mqsiservice -v

# Restrict permissions on file input directories
chown -R aceuser:acegroup /var/mqsi/inputs
chmod 750 /var/mqsi/inputs