CVE-2026-77254
Received Received - Intake

MCP Atlassian Unauthenticated Access to Tool Handlers

Publication date: 2026-09-22

Last updated on: 2026-09-22

Assigner: GitHub, Inc.

Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, requests to the HTTP MCP endpoint without a per-user identity are allowed to reach tool handlers, which then use globally configured Jira or Confluence credentials. A network caller can perform operations with the operator account's permissions unless the deployment has an independent authentication boundary. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, _get_fetcher, and global credentials, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-22
Last Modified
2026-09-22
Generated
2026-09-22
AI Q&A
2026-09-22
EPSS Evaluated
N/A
NVD
CVE-2026-77254
EUVD
EUVD-2026-84743

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
sooperset mcp-atlassian to 0.22.0 (exc)
atlassian mcp 0.22.0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-306 The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-77254 affects MCP Atlassian versions before 0.22.0. It allows unauthenticated remote attackers to send POST requests to the HTTP MCP endpoint without an Authorization header. The server binds to all interfaces by default, exposing it to the network. Without enforced authentication, requests fall back to globally configured Atlassian service account credentials, enabling unauthorized access to Jira or Confluence tools.

Detection Guidance

Check if your mcp-atlassian version is below 0.22.0 by running: pip show mcp-atlassian. Inspect network traffic for unauthenticated POST requests to the MCP HTTP endpoint. Verify if the server binds to all interfaces (0.0.0.0) and if global credentials are configured without authentication middleware.

Impact Analysis

An attacker could exploit this to perform unauthorized operations using the global service account's permissions. This includes reading or modifying issues, pages, comments, or attachments in Jira or Confluence without needing prior credentials. The attack is remote and requires no authentication.

Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, violating confidentiality and integrity requirements in GDPR and HIPAA. Unauthorized modifications or disclosures of sensitive data may result in non-compliance, potential fines, and reputational damage.

Mitigation Strategies

Upgrade mcp-atlassian to version 0.22.0 or later immediately. If upgrading is not possible, restrict the HTTP server to localhost (127.0.0.1) and enforce authentication middleware for the MCP endpoint. Disable global credentials if not required.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-77254. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart