MCP Atlassian: Multiple Critical Vulnerabilities in File Upload and SSRF

Three critical vulnerabilities discovered in mcp-atlassian package: path traversal allowing arbitrary file read via confluence_upload_attachment, SSRF protection bypass in URL validation, and unrestricted file upload allowing server-local file exfiltration to Jira/Confluence attachments.

Disclosed 22 September 2026 · Record updated 1 October 2026

Impact

Remote attackers can read arbitrary server files, bypass SSRF protections to access internal services, and upload server-local files to remote Jira/Confluence instances without authentication in default deployments.

Our coverage

A fortress wall crumbles in three places simultaneously: a thief slips through a crack reading scrolls, another dumps contraband through an opening, a third sneaks past guards into the inner chamber.

Vulnerabilities

Three critical flaws disclosed in MCP Atlassian server

Advisories published on 22 September 2026 describe arbitrary file reads, unrestricted uploads and an SSRF bypass in the popular mcp-atlassian connector, with no patch at disclosure.

22 Sept 2026

Sources

github.comhttps://github.com/advisories/GHSA-p6hp-93wp-fh6p
github.comhttps://github.com/advisories/GHSA-hgcf-4mq8-5266
github.comhttps://github.com/advisories/GHSA-f6pj-qv47-g96w