CVE-2026-77255

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.

• https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
• https://github.com/sooperset/mcp-atlassian/pull/1448
• https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0
• https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc
• https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc

• https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
• https://github.com/sooperset/mcp-atlassian/pull/1448
• https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0
• https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc
• https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc

• HIGHCVE-2026-77246PoC
• HIGHCVE-2017-20284
• MEDIUMCVE-2024-58386PoC
• MEDIUMCVE-2025-1280
• HIGHCVE-2025-1281
• HIGHCVE-2025-14753
• HIGHCVE-2026-100372PoC
• HIGHCVE-2026-100520PoC

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