CVE-2026-77255
Published:September 22, 2026
Updated:September 23, 2026
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.
Affected Packages
mcp-atlassian (CONDA):
Affected version(s) =0.21.1 <0.22.0Fix Suggestion:
Update to version 0.22.0https://github.com/sooperset/mcp-atlassian.git (GITHUB):
Affected version(s) >=v0.5.0 <v0.22.0Fix Suggestion:
Update to version v0.22.0mcp-atlassian (PYTHON):
Affected version(s) >=0.1.0 <0.22.0Fix Suggestion:
Update to version 0.22.0Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
9.2
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
HIGH
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
8.6
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE