CVE-2026-77243
Received Received - Intake

Privilege Escalation in MCP Atlassian Server

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, ENABLED_TOOLS and TOOLSETS are applied when tools are listed but are not rechecked when a tools/call request is dispatched. A client that knows a hidden tool name can directly invoke excluded read, write, or delete tools despite the operator's configured least-privilege restrictions. The advisory traces the vulnerable input and processing flow through ENABLED_TOOLS, TOOLSETS, tools/list, tools/call, and _call_tool_mcp, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

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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-2026-77243
EUVD
EUVD-2026-84626

Affected Vendors & Products

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

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

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Executive Summary

CVE-2026-77243 is an authorization bypass in MCP Atlassian versions prior to 0.22.0. It allows users with access to the MCP server's HTTP endpoint to directly invoke any of the 73 registered tools via the tools/call endpoint, bypassing ENABLED_TOOLS and TOOLSETS filters that are only enforced during tools/list. This enables unauthorized read, write, and delete operations on Jira issues and Confluence pages.

Detection Guidance

To detect this vulnerability, check the version of mcp-atlassian installed on your system. Run: mcp-atlassian --version. If the version is below 0.22.0, the system is vulnerable. Additionally, monitor HTTP endpoint logs for unauthorized tools/call requests to restricted tools.

Impact Analysis

This vulnerability allows attackers with access to the MCP server to perform unauthorized actions such as reading, modifying, or deleting sensitive data in Jira or Confluence. It undermines least-privilege access controls, potentially leading to data breaches, unauthorized modifications, or service disruption in multi-user environments.

Compliance Impact

This vulnerability can lead to unauthorized access and data exposure, violating compliance requirements for data protection such as GDPR (data confidentiality) and HIPAA (protected health information integrity). It undermines access controls and audit mechanisms, increasing the risk of non-compliance and potential regulatory penalties.

Mitigation Strategies

Upgrade mcp-atlassian to version 0.22.0 or later immediately. Disable the tools/call endpoint if not required. Review and restrict access to the MCP server's HTTP endpoint. Ensure ENABLED_TOOLS and TOOLSETS filters are properly configured and enforced.

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