CVE-2026-77248

HighCVSS 8.6/10Last modified Sep 28, 2026

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Metrics

CVSS 3.1 8.6/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Weakness enumeration

CWE-22CWE-306

Affected software

No affected versions have been published.

Timeline

Published
Sep 22, 2026
Last modified
Sep 28, 2026
NVD status
Analyzed

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CVE-2026-77248: High severity, CVSS 8.6 | Vulnix