CVE-2026-77253: mcp-atlassian Arbitrary File Read Vulnerability in Jira and Confluence Attachment Upload Tools
Summary
CVE-2026-77253: MCP Atlassian: Jira and Confluence attachment upload tools can read arbitrary server-local files. Affects mcp-atlassian versions < 0.22.0. Fixed in 0.22.0. How to fix ↓
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Background
The mcp-atlassian package provides tools for integrating with Atlassian products like Jira and Confluence. These tools facilitate the uploading of attachments to issues and pages within these platforms. However, a significant vulnerability exists that allows unauthorized file access on the server, potentially exposing sensitive data.
Vulnerability Detail
The vulnerability arises from the mcp-atlassian attachment upload tools in Jira and Confluence, which accept arbitrary local filesystem paths. This flaw allows an attacker with write access to the MCP tools to read any file accessible to the MCP process and upload its contents as an attachment. The implementation lacks proper validation of file paths, leading to a server-side arbitrary file read and exfiltration risk. The vulnerability is particularly severe in multi-user or HTTP deployments, where an attacker can exploit this flaw remotely.
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, set the environment variable READ_ONLY_MODE=true to block the attachment upload tools until the package can be updated.
Conclusion
CVE-2026-77253 represents a critical vulnerability in the mcp-atlassian package that can lead to unauthorized access to server files. It is essential to update to the patched version and implement the recommended workarounds to mitigate risks.
See every vulnerability recorded for mcp-atlassian →
FAQ
CVE-2026-77253 is a vulnerability in the mcp-atlassian package that allows arbitrary file reading from the server through the Jira and Confluence attachment upload tools.
Any deployment of the mcp-atlassian package that allows write access to the attachment upload tools is potentially affected, especially in multi-user or HTTP environments.
An attacker could exfiltrate sensitive files from the server, including secrets, configuration files, and other sensitive data, leading to severe security breaches.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The CVSS score of this vulnerability is 7.1, indicating a high severity level.
References
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