Unintended Proxy or Intermediary ('Confused Deputy') 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-20158874
- published27 Sept 2026
- disclosed22 Sept 2026
- creditUnknown
Introduced: 22 Sep 2026
NewCVE-2026-77246 (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 Unintended Proxy or Intermediary ('Confused Deputy') via the upload_attachment function in both the Jira and Confluence attachment modules, where a caller-supplied file_path argument is not validated against the working directory before the file is opened and sent to the Atlassian API. An attacker can supply an absolute path or a ../-traversal path to cause the server to read and exfiltrate arbitrary files from the host filesystem. When the server runs in HTTP transport mode, the attacker can additionally supply attacker-controlled service headers (X-Atlassian-Confluence-Url / X-Atlassian-Confluence-Personal-Token) to redirect the upload to an attacker-controlled endpoint, compounding the exfiltration.
Note: This is only exploitable in HTTP transport mode (streamable-http or sse) for the full unauthenticated remote attack path; the READ_ONLY_MODE option must also be false (the default) for write tools including attachment upload to be active.