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CVE-2026-77246

MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

CVSS 3.1 7.4 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

Historical advisory recorded 23 Oct 2026 15:48:27 UTC. Read the latest advisory.

cve-program · CVE-2026-77246

Published

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-77246

Published

mcp-atlassian

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "sooperset",
                    "product": "mcp-atlassian",
                    "versions": [
                        {
                            "version": "< 0.22.0",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON