CVE-2026-77257: mcp-atlassian Local File Disclosure Vulnerability
Summary
CVE-2026-77257: MCP Atlassian: HTTP upload tools accept arbitrary server-local file paths. 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 designed for HTTP/SSE deployment, enabling persistent, remote, and multi-user interactions with Atlassian products like Jira and Confluence. It facilitates attachment flows that allow users to upload files to issues and pages. However, the package has a critical vulnerability that permits authenticated users to exploit the system by accessing arbitrary server-local file paths, potentially exposing sensitive information.
Vulnerability Detail
The vulnerability arises from the lack of proper validation on file paths provided by users when uploading attachments in the mcp-atlassian package. Specifically, the package allows authenticated users to specify any server-local file path without restrictions, leading to local file disclosure. This can result in sensitive data exposure, such as API tokens and configuration files, especially in environments where Docker or Kubernetes are used to mount sensitive files. The issue is particularly severe in multi-user deployments where the attacker can access files that should be restricted to their own user context.
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, consider disabling server-local upload tools in HTTP transport mode unless a specific upload directory is configured. This can be done by setting an environment variable or modifying the configuration to restrict access to local file paths.
Conclusion
The mcp-atlassian package has a significant vulnerability that allows for local file disclosure through improper validation of user-supplied file paths. It is crucial to update to the patched version and implement necessary security measures to mitigate risks associated with this vulnerability.
See every vulnerability recorded for mcp-atlassian →
FAQ
CVE-2026-77257 is a vulnerability in the mcp-atlassian package that allows authenticated users to upload arbitrary server-local files, leading to potential local file disclosure.
The vulnerability can lead to the exposure of sensitive information such as API tokens, OAuth credentials, and other local secrets, especially in shared environments.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If immediate updating is not possible, consider implementing temporary workarounds such as disabling local file uploads or restricting access to sensitive directories.
The CVSS score of this vulnerability is 8.3, indicating a high severity level.
References
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