CVE-2026-26339: Alfresco Transformation Service RCE Flaw

CVE-2026-26339 Overview

Hyland Alfresco Transformation Service contains an argument injection vulnerability in the document processing functionality that allows unauthenticated attackers to achieve remote code execution. This vulnerability enables attackers to inject arbitrary command-line arguments into document transformation processes, potentially leading to complete system compromise without requiring any authentication credentials.

Critical Impact

Unauthenticated remote code execution allows attackers to take complete control of affected Alfresco Transformation Service instances, potentially compromising the entire document management infrastructure.

Affected Products

• Hyland Alfresco Transformation Service

Discovery Timeline

• 2026-02-19 - CVE-2026-26339 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2026-26339

Vulnerability Analysis

The vulnerability resides in the document processing functionality of Hyland Alfresco Transformation Service. This service is responsible for converting documents between various formats as part of the Alfresco content management platform. The argument injection flaw allows attackers to manipulate the command-line arguments passed to underlying document processing utilities without requiring authentication.

When the Transformation Service processes document transformation requests, it constructs command-line arguments for external document processing tools. Due to insufficient input validation and sanitization, attackers can inject additional arguments or modify existing ones, leading to arbitrary command execution in the context of the service.

The CWE-918 (Server-Side Request Forgery) classification associated with this vulnerability suggests that the argument injection may also be leveraged to force the server to make unauthorized requests to internal or external resources, expanding the attack surface beyond direct code execution.

Root Cause

The root cause of this vulnerability is improper input validation and sanitization in the document transformation request handler. When processing user-supplied document transformation parameters, the service fails to adequately sanitize special characters and command-line argument delimiters. This allows attackers to break out of the intended argument context and inject malicious arguments that are then passed to the underlying document processing utilities.

Attack Vector

This vulnerability is exploitable over the network without requiring authentication. An attacker can send specially crafted requests to the Alfresco Transformation Service endpoint, embedding malicious arguments within document transformation parameters. Since no authentication is required, any network-accessible instance of the vulnerable service is at risk. The attack requires no user interaction and can be automated for mass exploitation.

The exploitation process typically involves:

1. Identifying an exposed Alfresco Transformation Service endpoint
2. Crafting a malicious document transformation request with injected arguments
3. Sending the request to trigger arbitrary command execution on the target server

For technical details on the exploitation mechanism, refer to the VulnCheck Hyland Alfresco RCE Advisory.

Detection Methods for CVE-2026-26339

Indicators of Compromise

• Unusual process spawning from the Alfresco Transformation Service with unexpected command-line arguments
• Unexpected network connections originating from the Transformation Service to internal or external hosts
• Anomalous file system activity in transformation service directories including creation of unexpected files
• Unusual CPU or memory utilization patterns indicating potential cryptominer or backdoor activity

Detection Strategies

• Implement network monitoring to detect malformed or suspicious document transformation requests
• Deploy endpoint detection and response (EDR) solutions to monitor process execution chains from the Transformation Service
• Enable comprehensive logging for all document transformation requests including full request parameters
• Monitor for unexpected child processes spawned by the Transformation Service process

Monitoring Recommendations

• Configure alerting for command-line argument patterns containing shell metacharacters or escape sequences
• Monitor outbound network traffic from the Transformation Service for connections to unexpected destinations
• Implement file integrity monitoring on Transformation Service directories and configuration files
• Review access logs regularly for transformation requests from unexpected source IPs or containing unusual parameters

How to Mitigate CVE-2026-26339

Immediate Actions Required

• Restrict network access to the Alfresco Transformation Service to only trusted internal hosts
• Implement authentication requirements in front of the Transformation Service using a reverse proxy
• Review and audit all recent transformation requests for signs of exploitation
• Consider temporarily disabling the Transformation Service if not business-critical until a patch is available

Patch Information

Monitor the Hyland Alfresco Platform page for security updates addressing this vulnerability. Apply vendor-provided patches as soon as they become available. Review the VulnCheck advisory for the latest remediation guidance.

Workarounds

• Deploy a web application firewall (WAF) with rules to filter potentially malicious transformation requests
• Implement network segmentation to isolate the Transformation Service from critical systems
• Apply strict input validation at the network perimeter for all requests to the Transformation Service
• Consider containerizing the Transformation Service with minimal privileges to limit the impact of successful exploitation

# Example: Restrict access to Transformation Service using iptables
# Allow only specific internal hosts to access the service
iptables -A INPUT -p tcp --dport 8090 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8090 -j DROP

# Enable logging for blocked connection attempts
iptables -A INPUT -p tcp --dport 8090 -j LOG --log-prefix "Alfresco-Blocked: "