CVE-2026-13287: IBM MQ XXE Vulnerability

CVE-2026-13287 Overview

IBM MQ contains an XML External Entity (XXE) injection vulnerability in its XML data processing routines. A remote authenticated attacker can submit crafted XML input to expose sensitive information or exhaust memory resources on the affected message broker. The flaw is tracked as CWE-611: Improper Restriction of XML External Entity Reference and impacts multiple Long Term Support (LTS) and Continuous Delivery (CD) release trains, including IBM MQ 10.0.0.0.

Critical Impact
A remote attacker with low privileges can trigger XML entity expansion or out-of-band retrieval to disclose confidential data and degrade broker availability.

Affected Products

IBM MQ 9.1.0.0 through 9.1.0.37 LTS and 9.2.0.0 through 9.2.0.43 LTS
IBM MQ 9.3.0.0 through 9.3.0.41 LTS, 9.3.0.0 through 9.3.5.1 CD, 9.4.0.0 through 9.4.0.25 LTS, and 9.4.0.0 through 9.4.5.1 CD
IBM MQ 10.0.0.0

Discovery Timeline

2026-09-14 - CVE-2026-13287 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-13287

Vulnerability Analysis

IBM MQ processes XML documents through its administrative and messaging interfaces. The XML parser used by the affected components does not disable external entity resolution when handling untrusted input. An authenticated remote attacker can submit an XML payload that references external entities, causing the parser to fetch external resources or expand recursive entities.

Exploitation yields two primary outcomes. First, the parser can be coerced into reading local files or issuing outbound network requests, disclosing sensitive configuration data. Second, entity expansion patterns such as billion-laughs style payloads consume memory and degrade broker responsiveness.

The issue affects XML handling across LTS 9.1, 9.2, 9.3, 9.4, CD 9.3 and 9.4 streams, and the newer 10.0.0.0 release. Because IBM MQ commonly brokers traffic between trusted enterprise systems, a compromised queue manager can act as a pivot point for further reconnaissance.

Root Cause

The root cause is an insecurely configured XML parser [CWE-611]. External entity resolution and DOCTYPE processing are permitted on inbound XML data. Secure parser configuration requires disabling DOCTYPE, external general entities, and external parameter entities before parsing untrusted documents.

Attack Vector

Exploitation occurs over the network against an authenticated MQ interface that accepts XML input. The attacker submits a crafted document containing an external entity declaration or nested entity expansion. No user interaction is required, and the scope remains unchanged on the affected queue manager. Refer to the IBM Support Page for technical particulars on the affected interfaces.

Detection Methods for CVE-2026-13287

Indicators of Compromise

XML payloads received by IBM MQ containing <!DOCTYPE> declarations, <!ENTITY> references, or SYSTEM identifiers pointing to local paths or remote URLs.
Unexpected outbound network connections from the MQ queue manager process to attacker-controlled hosts during XML processing.
Sudden spikes in memory consumption, thread contention, or queue manager restarts correlated with inbound XML traffic.

Detection Strategies

Inspect MQ administrative and application traffic for XML documents containing DOCTYPE or ENTITY tokens using network detection tooling.
Correlate authentication events on MQ channels with XML message submission to identify low-privileged accounts issuing structured payloads.
Baseline normal MQ process memory and file descriptor usage to detect anomalies indicative of entity expansion attacks.

Monitoring Recommendations

Enable verbose MQ error logging (AMQERR01.LOG) and forward events to a centralized analytics platform for correlation.
Monitor outbound DNS and HTTP requests originating from the MQ host, which should be minimal during normal operation.
Alert on repeated parser exceptions or oversized XML payloads submitted through MQ channels or the admin interface.

How to Mitigate CVE-2026-13287

Immediate Actions Required

Apply the IBM MQ fix pack referenced in the IBM Support Page to all affected LTS, CD, and 10.0.0.0 deployments.
Restrict MQ channel authentication so only trusted service accounts can submit administrative or application XML payloads.
Segment MQ queue managers from arbitrary outbound internet access to blunt out-of-band XXE data exfiltration.

Patch Information

IBM has published remediation guidance and fix pack details on the IBM Support Page. Upgrade paths are provided for the 9.1, 9.2, 9.3, 9.4 LTS lines, the 9.3 and 9.4 CD lines, and the 10.0.0.0 release. Verify the installed version with dspmqver after patching.

Workarounds

Where patching is delayed, restrict access to MQ interfaces that accept XML input using channel authentication records (CHLAUTH) and IP allow-lists.
Place an application-layer gateway in front of MQ to strip DOCTYPE and ENTITY declarations from inbound XML.
Disable or throttle XML-consuming applications that route external traffic into MQ until fixes are validated.

bash

# Example: restrict an MQ channel to a trusted admin subnet
runmqsc QMGR1 <<EOF
SET CHLAUTH('SYSTEM.ADMIN.SVRCONN') TYPE(ADDRESSMAP) ADDRESS('10.20.30.*') USERSRC(CHANNEL) ACTION(REPLACE)
SET CHLAUTH('SYSTEM.ADMIN.SVRCONN') TYPE(BLOCKUSER) USERLIST('*NOACCESS') ACTION(REPLACE)
REFRESH SECURITY TYPE(CONNAUTH)
EOF