CVE-2025-53110: 
JavaScript vulnerability analysis and mitigation

The vulnerability CVE-2025-53110 is a directory containment bypass vulnerability discovered in Anthropic's Model Context Protocol (MCP) Filesystem Server. The flaw affects versions prior to 0.6.4 or 2025.7.01 and carries a CVSS score of 7.3 (High). The vulnerability allows attackers to access unintended files in cases where the prefix matches an allowed directory (GitHub Advisory, Hacker News).

The vulnerability exploits a directory containment bypass through naive prefix-matching validation. The Filesystem MCP Server uses a simple 'start with' check to verify if requested paths fall within allowed directories. For example, if '/private/tmp/allow_dir' is an allowed directory, an attacker can access '/private/tmp/allow_dir_sensitive_credentials' since the malicious path begins with the approved prefix. The vulnerability has been assigned a CVSS v4.0 base score of 7.3 with the vector string: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:H/SI:H/SA:H (Cybersecurity News).

The vulnerability enables attackers to break out of the server's sandbox and access files outside of the approved directory structure. In setups where the server runs as a privileged user, this flaw could lead to privilege escalation, allowing attackers to manipulate critical system files and gain deeper control over the host system. The vulnerability potentially enables data theft and possible privilege escalation through unauthorized access to sensitive files and configurations (Hacker News).

Users are advised to upgrade to version 0.6.4 or 2025.7.01, which contain the necessary fixes for this vulnerability. The patches were released on July 1, 2025. Organizations should immediately upgrade their MCP implementations and apply the principle of least privilege to limit potential exploitation impact (Cybersecurity News).

Security researcher Elad Beber described CVE-2025-53110 as "a serious breach of the Filesystem MCP Servers security model," highlighting the potential for attackers to gain unauthorized access by listing, reading, or writing to directories outside the allowed scope. The vulnerability has raised concerns about the security implications for AI systems gaining deeper integration with critical infrastructure (Hacker News).