Missing Authentication for Critical Function Affecting mcp-atlassian package, versions [,0.22.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-MCPATLASSIAN-20158881
- published27 Sept 2026
- disclosed22 Sept 2026
- creditUnknown
Introduced: 22 Sep 2026
NewCVE-2026-77254 (opens in a new tab)How to fix?
Upgrade mcp-atlassian to version 0.22.0 or higher.
Overview
mcp-atlassian is a The Model Context Protocol (MCP) Atlassian integration is an open-source implementation that bridges Atlassian products (Jira and Confluence) with AI language models following Anthropic's MCP specification. This project enables secure, contextual AI interactions with Atlassian tools while maintaining data privacy and security. Key features include:
Affected versions of this package are vulnerable to Missing Authentication for Critical Function via a caller-supplied file_path argument in the upload_attachment function in both src/mcp_atlassian/confluence/attachments.py and src/mcp_atlassian/jira/attachments.py. The function previously converted relative paths to absolute paths without confining them to the working directory, allowing an attacker to supply an absolute path or a ../-traversal path that causes the server to read and exfiltrate arbitrary files from the host filesystem. Because the main HTTP server has no FastMCP authentication provider enforced by default, a network caller can trigger this path with operator-level permissions.
Note: This is only exploitable when the deployment does not have an independent authentication boundary and ATLASSIAN_OAUTH_PROXY_ENABLE is not explicitly set to true.