Is CVE-2026-77266 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-77266?

CVE-2026-77266 has a CVSS v3 severity of MEDIUM (6.5).

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CVE-2026-77266

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment accepts absolute paths and traversal sequences without constraining the resolved path to the server workspace. An MCP caller with attachment access can read a chosen server-local file and exfiltrate it through Jira or Confluence. The advisory traces the vulnerable input and processing flow through upload_attachment, file_path, and path traversal, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.