CVE-2026-49471 in Serena
Summary
by MITRE • 07/08/2026
Serena is a powerful MCP toolkit for coding that provides semantic retrieval and editing capabilities. Prior to v1.5.2, Serena's built-in web dashboard exposes an unauthenticated Flask API on a fixed, predictable port, with no authentication, no CSRF protection, and no Host header validation. A DNS rebinding attack allows a malicious webpage to reach this API from any browser and write arbitrary content to the agent's persistent memory store, which the agent reads and acts on autonomously. Combined with execute_shell_command using shell=True, this creates a remote code execution chain requiring only that the victim visit a malicious webpage while Serena is running. This issue is fixed in version v1.5.2.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 07/08/2026
The vulnerability in Serena's web dashboard represents a critical security flaw that stems from improper API design and insufficient access controls within the application's architecture. Prior to version 1.5.2, the toolkit's built-in web interface exposed a Flask API endpoint on a fixed, predictable port without any authentication mechanisms, CSRF protections, or host header validation checks. This configuration creates an inherently insecure attack surface where any remote attacker can directly interact with the underlying API without requiring credentials or authorization tokens. The predictable port exposure violates fundamental security principles for service availability and access control, as it eliminates any obscurity-based defense that might have otherwise provided minimal protection against automated scanning.
The technical exploitation of this vulnerability relies on DNS rebinding attacks, which leverage the browser's handling of DNS resolution to bypass traditional network security boundaries. When a victim visits a malicious webpage while Serena is running, the attacker can manipulate DNS responses to redirect requests from the malicious site to the local Serena dashboard API. This technique exploits the browser's behavior in handling DNS lookups and HTTP connections, allowing the attacker to establish communication with the locally exposed API endpoint despite network-level firewalls or security restrictions. The lack of host header validation in the Flask application means that the system cannot properly verify the origin of requests, creating an avenue for attackers to impersonate legitimate internal services.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it creates a complete remote code execution chain when combined with existing functionality within Serena's architecture. The exposed API allows arbitrary content writing to the agent's persistent memory store, which the agent autonomously reads and executes as part of its normal operation. This persistent storage mechanism becomes a critical attack vector where malicious payloads can be stored and later retrieved by the agent during subsequent operations. When combined with the execute_shell_command function using shell=True parameter, attackers can execute arbitrary commands on the system running Serena, effectively providing complete control over the host machine. This combination of vulnerabilities demonstrates how seemingly isolated security flaws can create cascading effects that result in full system compromise.
The mitigation for this vulnerability requires implementing proper authentication mechanisms, input validation, and network isolation controls as recommended by industry standards such as CWE-284 for improper access control and CWE-352 for cross-site request forgery. The fix implemented in version 1.5.2 addresses these issues by introducing proper authentication requirements for API access, adding CSRF protection measures, and implementing host header validation to prevent DNS rebinding attacks from succeeding. Organizations using Serena should ensure they upgrade to version 1.5.2 or later, while also implementing network segmentation controls that prevent unauthorized access to the dashboard port from external networks. This vulnerability aligns with ATT&CK techniques related to initial access through web application exploitation and privilege escalation via command execution, highlighting the importance of securing all exposed interfaces in automated systems that can execute arbitrary code based on user input or configuration data.