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 could allow an authenticated attacker with MFT publish authority to obtain sensitive information or cause a denial of service due to XML external entity injection in the mqweb MFT REST API.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.8",
  "pubDate": "2026-09-14T22:16:57.100Z",
  "pubdate": "2026-09-14T22:16:57.100Z",
  "executiveSummary": "A critical security vulnerability identified as XML External Entity (XXE) injection exists within the IBM MQ mqweb MFT REST API.\nThis vulnerability allows an authenticated attacker possessing MFT publish authority to execute arbitrary XML parsing tasks, leading to the unauthorized disclosure of sensitive server-side information or a Denial of Service (DoS) condition.\nThe flaw affects multiple versions across LTS (Long Term Support) and CD (Continuous Delivery) release streams, specifically IBM MQ 9.1.0.0 through 9.4.0.25 LTS and 9.3.0.0 through 9.4.5.1 CD, as well as 10.0.0.0.\nThe risk is primarily realized through the improper handling of XML input during Managed File Transfer (MFT) REST API calls, where the parser fails to restrict the processing of external entities.\nSuccessful exploitation requires the attacker to have established authenticated access to the system with specific MFT publishing permissions.\nThe vulnerability poses significant security risks to data confidentiality and service availability, necessitating prompt remediation.",
  "technicalDetails": "The vulnerability originates from the insecure configuration or implementation of the XML parser utilized by the mqweb MFT REST API component in IBM MQ. Specifically, the parser is configured to resolve external entities defined within an XML document during the deserialization or processing of user-supplied input.\nAn XXE injection occurs when an XML parser, which processes XML data, is not explicitly configured to disable DTD (Document Type Definition) processing or external entity expansion. By injecting a crafted XML payload containing an external entity definition (e.g., <!ENTITY xxe SYSTEM 'file:///etc/passwd'>), an attacker can coerce the server into processing the entity during document parsing.\nThe attack flow proceeds as follows: First, the attacker, already possessing the required MFT publish authority, crafts a malicious REST request containing an XML payload directed at the MFT REST API endpoint. The payload includes a DTD that specifies an external system or file resource. Upon receipt, the mqweb component invokes the vulnerable XML parser to interpret the request. The parser resolves the external entity by attempting to retrieve the content of the specified URI or file path. If the parser is configured to return the content of the entity, the server may reflect the sensitive file contents back to the attacker in the HTTP response. If the attacker references a non-existent or malicious resource (such as a local system device or an infinite loop), it can induce resource exhaustion, leading to a Denial of Service.\nThe vulnerability exists within the mqweb MFT REST API, which handles administrative and operational tasks for Managed File Transfer. Because the API requires authentication, the attack surface is limited to authenticated users who have been granted MFT publish authority. Once authenticated, the attacker does not need further escalation to exploit the parser; the authority to publish provides the necessary access to submit the XML payloads that trigger the flaw.\nAffected software versions include broad ranges across multiple release cycles: 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. The failure to sanitize these inputs allows for local file inclusion (LFI) style data exfiltration and potential service degradation through recursive entity expansion or network-based SSRF.\nThe post-exploitation impact includes the exposure of system configuration files, credentials, or other sensitive data residing on the IBM MQ server, depending on the file system permissions of the user account running the mqweb service, as well as the potential for complete system instability."
}