Cursor up to 1.3.8 MCP File Parser /.Cursor/mcp.json os command injection

Summaryinfo

A vulnerability was found in Cursor up to 1.3.8. It has been classified as critical. The impacted element is an unknown function of the file /.Cursor/mcp.json of the component MCP File Parser. The manipulation leads to os command injection. This vulnerability is listed as CVE-2025-54135. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Cursor up to 1.3.8. It has been rated as critical. This issue affects an unknown code block of the file /.Cursor/mcp.json of the component MCP File Parser. The manipulation with an unknown input leads to a os command injection vulnerability. Using CWE to declare the problem leads to CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Cursor is a code editor built for programming with AI. Cursor allows writing in-workspace files with no user approval in versions below 1.3.9, If the file is a dotfile, editing it requires approval but creating a new one doesn't. Hence, if sensitive MCP files, such as the .cursor/mcp.json file don't already exist in the workspace, an attacker can chain a indirect prompt injection vulnerability to hijack the context to write to the settings file and trigger RCE on the victim without user approval. This is fixed in version 1.3.9.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-54135 since 07/17/2025. The exploitation is known to be difficult. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

By approaching the search of inurl:.Cursor/mcp.json it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 1.3.9 eliminates this vulnerability.

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Productinfo

Name

• Cursor

Version

• 1.3.0
• 1.3.1
• 1.3.2
• 1.3.3
• 1.3.4
• 1.3.5
• 1.3.6
• 1.3.7
• 1.3.8

Website

• Product: https://github.com/cursor/cursor/

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