Description

IBM MQ 9.1.0.0 through 9.1.0.37 LTS, 9.2.0.0 through 9.2.0.43 LTS, 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, 9.4.0.0 through 9.4.5.1 CD, and 10.0.0.0 is vulnerable to an XML external entity injection (XXE) attack when processing XML data. A remote attacker could exploit this vulnerability to expose sensitive information or consume memory resources.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-09-14T21:17:01.977Z",
  "pubdate": "2026-09-14T21:17:01.977Z",
  "executiveSummary": "This vulnerability is an XML External Entity (XXE) injection flaw identified in various versions of IBM MQ. The vulnerability arises from improper validation of XML data processed by the application, allowing an attacker to manipulate the XML parser's behavior.\nA remote, unauthenticated attacker can exploit this flaw to perform unauthorized actions, including the disclosure of sensitive server-side information or the orchestration of a Denial of Service (DoS) attack through resource exhaustion.\nThe affected product lines include IBM MQ 9.1.0.0 through 9.1.0.37 (LTS), 9.2.0.0 through 9.2.0.43 (LTS), 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), 9.4.0.0 through 9.4.5.1 (CD), and version 10.0.0.0.\nThe risk implication is critical, as it compromises the confidentiality and availability of the messaging infrastructure. Attackers do not necessarily require high-level privileges to initiate the exploitation if they can send crafted XML payloads to the vulnerable interface.\nSuccessful exploitation allows for the potential reading of arbitrary local files on the host system or excessive memory consumption, which can destabilize the message queuing service.",
  "technicalDetails": "The vulnerability originates from the insecure configuration or implementation of the XML parser utilized by IBM MQ during the ingestion and processing of XML-formatted data packets. Specifically, the XML parser fails to properly disable the resolution of external entities, which is a foundational security requirement when parsing untrusted XML input.\nAn XML External Entity (XXE) injection occurs when an attacker defines custom entities within the Document Type Definition (DTD) of an XML document. By injecting a crafted DTD, the attacker forces the XML processor to follow URI references to internal or external resources. When the parser resolves these entities, it attempts to retrieve the contents of the specified resource.\nIn the context of IBM MQ, the attack flow begins with the submission of a malicious XML payload directed at an interface that parses incoming messages. The payload includes a DOCTYPE declaration defining an external entity pointing to a local file path (e.g., /etc/passwd or critical configuration files) or an internal network resource accessible to the server. Because the parser is configured to process these entities, it attempts to resolve the URI.\nIf the entity points to a local file, the parser may include the content of that file within the XML response or log, leading to sensitive information disclosure. Alternatively, an attacker can leverage this mechanism to trigger an out-of-band (OOB) request to a server controlled by the attacker, effectively mapping internal network infrastructure or bypassing firewalls.\nFurthermore, the vulnerability enables Denial of Service (DoS) scenarios. By defining an entity that points to a resource such as /dev/random or a massive data stream, the attacker can cause the parser to consume excessive memory or CPU cycles. This is often achieved through 'XML Bomb' tactics, where recursive entity expansion forces the parser to allocate memory beyond established thresholds, leading to service failure.\nThe vulnerability is pervasive across the specified LTS and CD (Continuous Delivery) branches because these versions likely utilize the same underlying XML processing library or shared component logic without adequate sanitization settings. The exploit is typically remote and does not require complex authentication mechanisms, making the attack surface significantly large for environments where IBM MQ instances are exposed to untrusted network segments."
}