CVE-2026-1567: IBM InfoSphere Information Server XXE Flaw

CVE-2026-1567 Overview

An XML External Entity (XXE) vulnerability has been identified in IBM InfoSphere Information Server versions 11.7.0.0 through 11.7.1.6. This vulnerability could allow unauthenticated attackers to retrieve sensitive information from the server by exploiting improper handling of XML input. XXE attacks occur when XML parsers process external entity references within XML documents, potentially exposing internal files, network resources, and system configurations.

Critical Impact

Attackers can exploit this XXE vulnerability to exfiltrate sensitive data including configuration files, credentials, and internal system information from IBM InfoSphere Information Server deployments without authentication.

Affected Products

• IBM InfoSphere Information Server 11.7.0.0
• IBM InfoSphere Information Server 11.7.1.x through 11.7.1.6
• IBM InfoSphere Information Server (all components processing XML input)

Discovery Timeline

• 2026-03-03 - CVE-2026-1567 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-1567

Vulnerability Analysis

This vulnerability is classified as CWE-611 (Improper Restriction of XML External Entity Reference). The flaw exists in how IBM InfoSphere Information Server processes XML input, failing to properly disable or restrict external entity processing. When an application parses XML input containing a reference to an external entity, the XML parser attempts to resolve and include the referenced content, which can be leveraged by attackers to access files on the local system or make outbound network requests.

The network-accessible nature of this vulnerability means that attackers can exploit it remotely without requiring any prior authentication or user interaction. The impact is primarily on confidentiality, as successful exploitation leads to unauthorized information disclosure.

Root Cause

The root cause of this vulnerability lies in the insecure configuration of XML parsers within IBM InfoSphere Information Server. The application fails to disable Document Type Definition (DTD) processing and external entity resolution in its XML parsing components. This allows malicious XML payloads containing external entity declarations to be processed, enabling attackers to reference and retrieve sensitive resources.

Proper secure XML parsing requires explicitly disabling features such as:

• External general entities
• External parameter entities
• DTD processing
• XInclude processing

Attack Vector

The attack leverages network access to XML processing endpoints within IBM InfoSphere Information Server. An attacker crafts a malicious XML document containing external entity declarations that reference sensitive system files (such as /etc/passwd on Unix systems or configuration files containing credentials). When the vulnerable application parses this XML input, the parser resolves the external entity reference and includes the file contents in the response or processing output.

This XXE vulnerability can also be exploited for Server-Side Request Forgery (SSRF) attacks, where the attacker forces the server to make HTTP requests to internal network resources, potentially exposing additional attack surface.

Detection Methods for CVE-2026-1567

Indicators of Compromise

• Unusual XML payloads in application logs containing <!DOCTYPE declarations with ENTITY definitions
• Server requests to unexpected internal file paths such as /etc/passwd, /etc/shadow, or Windows configuration files
• Outbound HTTP/HTTPS connections from the InfoSphere server to unexpected external hosts
• Error messages revealing local file system paths or internal network information

Detection Strategies

• Monitor web application firewall (WAF) logs for XML payloads containing <!ENTITY declarations or DTD references
• Implement content inspection rules to detect common XXE payloads including file://, php://, expect://, and other protocol handlers
• Configure SIEM rules to alert on InfoSphere server processes accessing sensitive system files
• Deploy endpoint detection to monitor for unusual file access patterns by the InfoSphere application

Monitoring Recommendations

• Enable detailed XML parsing logging within IBM InfoSphere Information Server where available
• Monitor network traffic for unexpected outbound connections originating from the InfoSphere server
• Implement file integrity monitoring on sensitive configuration files to detect unauthorized access attempts
• Review application access logs for anomalous XML submissions to data integration endpoints

How to Mitigate CVE-2026-1567

Immediate Actions Required

• Apply the security patch from IBM immediately by following the guidance in the IBM Support Advisory
• Implement network segmentation to restrict access to IBM InfoSphere Information Server from untrusted networks
• Deploy web application firewall rules to block XML payloads containing external entity declarations
• Audit all XML processing endpoints and restrict access to authenticated users only

Patch Information

IBM has released a security update addressing this vulnerability. Administrators should consult the IBM Support Page for detailed patching instructions and download links. The patch addresses the underlying XML parser configuration to properly disable external entity processing.

Affected organizations should upgrade IBM InfoSphere Information Server to a patched version as soon as possible, following standard change management procedures.

Workarounds

• Configure XML parsers to disable DTD processing and external entity resolution at the application level if custom configurations are supported
• Implement strict input validation to reject XML documents containing DOCTYPE declarations
• Deploy a reverse proxy or WAF with rules to strip or block XML payloads containing entity declarations
• Restrict network access to InfoSphere endpoints using firewall rules to limit exposure to trusted sources only

# Example WAF rule configuration to detect XXE payloads
# Add to your WAF configuration to block common XXE attack patterns
# ModSecurity rule example:
SecRule REQUEST_BODY "<!ENTITY" "id:100001,phase:2,deny,status:403,msg:'Potential XXE Attack Detected'"
SecRule REQUEST_BODY "SYSTEM\s+[\"']file:" "id:100002,phase:2,deny,status:403,msg:'XXE File Protocol Detected'"