Embrace The Red: Cline: Vulnerable To Data Exfiltration And How To Protect Your Data

Aug 27, 2025

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Source URL: https://embracethered.com/blog/posts/2025/cline-vulnerable-to-data-exfiltration/
Source: Embrace The Red
Title: Cline: Vulnerable To Data Exfiltration And How To Protect Your Data

Feedly Summary: Cline is quite a popular AI coding agent, according to the product website it has 2+ million downloads and over 47k stars on GitHub.
Unfortunately, Cline is vulnerable to data exfiltration through the rendering of markdown images from untrusted domains in the chat box.
This allows an adversary to exfiltrate sensitive user information during a prompt injection attack by reading sensitive data (e.g. .env file) and appending its contents to the URL of an image.

AI Summary and Description: Yes

Short Summary: The text discusses vulnerabilities in Cline, an AI coding agent that has gained significant traction, highlighting a serious security risk related to data exfiltration through markdown image rendering from untrusted domains. This is particularly relevant for professionals concerned with AI security and software vulnerabilities.

Detailed Description: The security issues surrounding Cline, an AI coding agent that has achieved considerable popularity, are critical for professionals in the fields of AI security and software security. Here are the major points highlighted in the content:

– **Popularity of Cline**:
– Cline has over 2 million downloads, indicating broad adoption.
– It has garnered over 47,000 stars on GitHub, a sign of community validation and interest.

– **Vulnerability Details**:
– The primary vulnerability identified is related to data exfiltration.
– This occurs through the rendering of markdown images sourced from untrusted domains within the application’s chat box.

– **Attack Vector**:
– Adversaries can exploit this flaw via a prompt injection attack.
– They can read sensitive data files (such as the .env file) that contain user-specific information.
– Attackers can append this sensitive data to the URL of an image, effectively transmitting it beyond the confines of the application to external servers.

– **Implications for Security**:
– This vulnerability raises serious concerns for software security, as it can lead to unauthorized data access.
– Security professionals must implement measures to secure AI applications against similar attack vectors to safeguard user information and maintain trust.

Given the increasing reliance on AI tools like Cline for coding assistance, understanding and addressing such vulnerabilities is crucial for maintaining the integrity and security of software development practices.

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