CVE-2026-77255

High

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementation without workspace validation. A caller can make the MCP server read arbitrary local files and attach them to a Jira issue, using the server as a confused deputy to exfiltrate the contents. The advisory traces the vulnerable input and processing flow through jira update_issue, attachments, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

SeverityHigh
CVSS8.6
Exploit probability—
ProductMcp-atlassian Mcp Atlassian
PublishedSep 22, 2026
First seenSep 22, 2026

How to fix

Update
  • mcp-atlassian mcp_atlassian0.22.0 or later
  • mcp-atlassian0.22.0 or later

Affected products

ProductAffected versionsFixed in
mcp-atlassian mcp_atlassianv < 0.22.00.22.0
mcp-atlassianPyPIv < 0.22.00.22.0

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CVE-2026-77255 · Mcp-atlassian Mcp Atlassian · Dark Radar