cyfenced.com →

[ CVE-2026-77258 · Published 22 Sep 2026 ]

MCP Atlassian: Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path()

CVSS 7.7 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment in src/mcp_atlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the workspace. A permitted Confluence MCP caller can upload the file as an attachment and disclose data readable by the server process. This issue is fixed in version 0.22.0.

[ Fixes ]Fixes and patches

  • mcp-atlassian 0.22.0Fixed version · GitHub Advisories · pip package mcp-atlassian: upgrade to 0.22.0 or later (affected < 0.22.0)

[ Packages ]Affected open-source packages

[ References ]References