CVE-2026-77270: mcp-atlassian Arbitrary File Read via Upload Attachment Tools
Summary
CVE-2026-77270: MCP Atlassian: Arbitrary File Read via Upload Attachment Tools. Affects mcp-atlassian versions < 0.22.0. Fixed in 0.22.0. How to fix ↓
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Background
The mcp-atlassian package is a Python library that integrates with Atlassian products like Confluence and Jira, enabling users to manage content and issues programmatically. This package allows for file uploads as attachments to Confluence pages and Jira issues, which is a common feature for enhancing collaboration and documentation. However, it has a critical vulnerability that permits unauthorized file access due to insufficient path validation during the upload process.
Vulnerability Detail
The vulnerability arises from the upload attachment methods in both Confluence and Jira, which accept arbitrary file paths without proper validation against path traversal attacks. This oversight allows authenticated users, or even AI assistants manipulated through prompt injection, to read and exfiltrate sensitive files from the server's filesystem. Files such as /etc/passwd or environment configuration files can be accessed and uploaded to attacker-controlled pages or issues, leading to potential credential theft and data exposure. The lack of a call to the validate_safe_path function in the upload process is the root cause of this vulnerability.
How To Fix
Latest published version: 0.23.1 as of 23 Oct 2026
pip install --upgrade "mcp-atlassian==0.23.1"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.22.0
This is the first release that contains the fix.
pip install --upgrade "mcp-atlassian==0.22.0"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, restrict access to the upload functionality to trusted users only. Additionally, implement server-side file access controls to prevent unauthorized file reads until the package can be updated.
Conclusion
The mcp-atlassian package has a significant vulnerability that allows arbitrary file reads through its upload attachment tools in Confluence and Jira. It is crucial for users to update to the patched version and implement recommended fixes to secure their applications against potential data breaches.
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FAQ
CVE-2026-77270 is a vulnerability in the mcp-atlassian package that allows arbitrary file reads via the upload attachment tools in Confluence and Jira.
If your application uses the mcp-atlassian package, it may allow authenticated users to exfiltrate sensitive files from the server, leading to potential data breaches.
Update the mcp-atlassian package to version 0.22.0 or later to mitigate the vulnerability. You can do this using 'pip install --upgrade mcp-atlassian'.
Yes, you can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring a signup.
The CVSS score of this vulnerability is 6.5, indicating a moderate severity level.
References
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