CVE-2026-77244

Critical

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the HTTP transport accepts requests without a verified user identity and downstream fetcher construction falls back to the operator's globally configured Jira or Confluence credentials. A network client that can reach the MCP endpoint can invoke Atlassian tools as the operator, including read and write operations available to that account. The advisory traces the vulnerable input and processing flow through UserTokenMiddleware, AtlassianOpaqueTokenVerifier, _get_fetcher, and streamable-http, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

SeverityCritical

CVSS10.0

Exploit probability—

ProductMcp-atlassian Mcp Atlassian

PublishedSep 22, 2026

First seenSep 22, 2026

Weakness typeCWE-287Improper authentication CWE-303CWE-303 CWE-862Missing authorization

How to fix

Update

mcp-atlassian mcp_atlassian0.22.0 or later
mcp-atlassian0.22.0 or later

Affected products

Product	Affected versions	Fixed in
mcp-atlassian mcp_atlassian	v < 0.22.0	0.22.0
mcp-atlassianPyPI	v < 0.22.0	0.22.0

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