CVE-2026-2097: Agentflow Arbitrary File Upload RCE Flaw

CVE-2026-2097 Overview

Agentflow, a business process management (BPM) solution developed by Flowring, contains an Arbitrary File Upload vulnerability (CWE-434) that allows authenticated remote attackers to upload and execute web shell backdoors on the server. This critical flaw enables arbitrary code execution, potentially giving attackers full control over the affected system and any data it processes.

Critical Impact

Authenticated attackers can upload malicious web shells to achieve remote code execution, leading to complete server compromise, data exfiltration, and lateral movement within the network.

Affected Products

• Flowring Agentflow (specific versions not disclosed)

Discovery Timeline

• 2026-02-10 - CVE-2026-2097 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2026-2097

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type), a well-documented weakness that occurs when an application allows users to upload files without adequately validating file type, content, or destination. In the case of Agentflow, authenticated users can exploit insufficient file upload validation controls to upload executable web shell scripts directly to the server's web-accessible directory.

Once a malicious web shell is uploaded, the attacker can access it via a web browser, effectively gaining a command-and-control interface to the server. This enables execution of arbitrary system commands, installation of additional malware, credential harvesting, and pivoting to other systems on the network. The network-based attack vector with low complexity makes this vulnerability particularly dangerous for organizations with internet-exposed Agentflow deployments.

Root Cause

The root cause stems from improper input validation during the file upload process. The application fails to implement adequate server-side validation checks for uploaded file types, extensions, and content. This allows attackers to bypass any client-side restrictions and upload executable scripts (such as JSP, PHP, or ASPX web shells depending on the server technology) that the web server subsequently interprets and executes.

Attack Vector

The attack requires authentication to the Agentflow application, meaning attackers must first obtain valid credentials through phishing, credential stuffing, or other means. Once authenticated, the attacker identifies a file upload functionality within the application and crafts a malicious web shell payload. By manipulating the upload request—potentially changing file extensions, content-type headers, or using null byte injection—the attacker uploads the web shell to a location accessible via HTTP/HTTPS.

The exploitation flow typically involves:

1. Authenticating to the Agentflow application with valid credentials
2. Locating file upload functionality (document attachments, profile images, etc.)
3. Crafting a web shell payload disguised to bypass validation
4. Uploading the malicious file to a web-accessible directory
5. Accessing the uploaded web shell via direct URL to execute commands

For detailed technical information, refer to the TWCert Security Advisory.

Detection Methods for CVE-2026-2097

Indicators of Compromise

• Unusual file uploads with executable extensions (.jsp, .php, .aspx, .war) in application upload directories
• Web shell signatures in uploaded files containing command execution functions or encoded payloads
• Unexpected outbound connections from the web server to external IP addresses
• Anomalous process spawning from the web server process (e.g., cmd.exe, /bin/sh, PowerShell)

Detection Strategies

• Monitor file upload activities for suspicious file types and content patterns using file integrity monitoring solutions
• Implement web application firewall (WAF) rules to detect and block web shell upload attempts
• Analyze web server access logs for requests to newly created files in upload directories
• Deploy endpoint detection and response (EDR) solutions to identify post-exploitation behavior such as command execution from web processes

Monitoring Recommendations

• Enable detailed logging for all file upload operations including file names, sizes, and user context
• Configure alerts for file creation events in web-accessible directories, particularly for executable file types
• Monitor network traffic for command-and-control patterns originating from the Agentflow server
• Regularly scan upload directories for known web shell signatures and suspicious files

How to Mitigate CVE-2026-2097

Immediate Actions Required

• Restrict network access to Agentflow instances to trusted networks only until patches are applied
• Review and audit all recently uploaded files for malicious content
• Implement strict file type whitelisting at the web application firewall level
• Disable or restrict file upload functionality if not business-critical

Patch Information

Organizations should monitor Flowring's official channels and the TWCert Security Advisory for patch availability. Apply vendor-provided security updates as soon as they become available. Contact Flowring support directly for guidance on remediation timelines and interim protective measures.

Workarounds

• Implement server-side file type validation using allowlists for permitted file extensions and MIME types
• Configure the web server to prevent script execution in upload directories (e.g., disable PHP/JSP handlers)
• Store uploaded files outside the web root directory to prevent direct access
• Deploy a web application firewall (WAF) with rules to detect and block web shell signatures in file uploads
• Enforce strong authentication controls and monitor for compromised credentials

# Example: Apache configuration to disable script execution in uploads directory
<Directory "/var/www/agentflow/uploads">
    Options -ExecCGI -Indexes
    AllowOverride None
    RemoveHandler .php .phtml .php3 .php4 .php5 .jsp .jspx
    <FilesMatch "\.(php|phtml|php3|php4|php5|jsp|jspx)$">
        Require all denied
    </FilesMatch>
</Directory>