Executive Summary

[{'type': 'paragraph', 'content': 'CVE-2026-27605 is a stored Cross-Site Scripting (XSS) vulnerability in the Chartbrew web application versions prior to 4.8.4. The application allows users to upload files, such as project logos, without validating the actual file type or content, relying only on the file extension provided by the user.'}, {'type': 'paragraph', 'content': "Because these files are saved in the uploads/ directory and served statically, an attacker can upload a malicious HTML file containing JavaScript code. When this file is accessed, the malicious script executes in the victim's browser under the application's domain."}, {'type': 'paragraph', 'content': 'Since authentication tokens are likely stored in localStorage and returned in the API response body, the malicious script can steal these tokens, potentially leading to account takeover.'}] [1]

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Impact Analysis

This vulnerability can have several impacts on users and administrators of the Chartbrew application.

• An attacker can steal authentication tokens or cookies, leading to account takeover.
• The attacker can deface content within the application.
• Keylogging can be performed to capture sensitive user input.
• Phishing forms can be injected to trick users into revealing sensitive information.
• Users can be redirected to malicious websites.

Additionally, the attack does not require the victim to be authenticated to trigger the XSS payload, increasing the risk and attack surface.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by checking if the application allows uploading files without validating their type or content, especially if files are saved in the uploads/ directory and served statically.'}, {'type': 'paragraph', 'content': 'One approach is to look for suspicious HTML or JavaScript files in the uploads/ directory that could contain malicious scripts.'}, {'type': 'paragraph', 'content': 'You can also monitor HTTP requests to the uploads/ directory for files with unexpected extensions or content.'}, {'type': 'list_item', 'content': 'Use a command to list files in the uploads directory, for example: ls -l /path/to/chartbrew/uploads/'}, {'type': 'list_item', 'content': 'Use curl or wget to fetch files from the uploads directory and inspect their content, e.g.: curl http://your-chartbrew-instance/uploads/suspicious-file.html'}, {'type': 'list_item', 'content': "Search for HTML or JavaScript content in the uploads directory using grep, e.g.: grep -r '<script' /path/to/chartbrew/uploads/"}, {'type': 'paragraph', 'content': 'Additionally, reviewing application logs for file upload activities and inspecting the file extensions and contents can help detect exploitation attempts.'}] [1]

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Mitigation Strategies

The immediate step to mitigate this vulnerability is to upgrade Chartbrew to version 4.8.4 or later, where the issue has been patched.

Until the upgrade can be applied, restrict file uploads to only allow safe file types and implement server-side validation to verify file content, not just the extension.

Additionally, consider restricting access to the uploads/ directory or serving uploaded files in a way that prevents execution of scripts.

Monitor and remove any suspicious files found in the uploads/ directory that could contain malicious scripts.

Inform users about the risk and encourage them to be cautious with files uploaded to the application.

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