CVE-2026-77267
Received Received - Intake

Server-Side Request Forgery in MCP Atlassian

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, the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers are processed by _process_authentication_headers and used to construct Atlassian fetchers without calling validate_url_for_ssrf. A caller who can set these headers can supply an internal or metadata-service URL and cause the server to send requests to that destination, bypassing the incomplete CVE-2026-27826 remediation. 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-2026-77267
EUVD
EUVD-2026-84621

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
atlassian mcp to 0.22.0 (exc)
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-918 The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Attack-Flow Graph

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Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in the MCP Atlassian package. It allows attackers to specify arbitrary URLs, including internal or private addresses, which the server then accesses on their behalf. The issue arises because the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers are processed without proper validation before being used to construct Atlassian fetchers.

Detection Guidance

Check if your mcp-atlassian version is below 0.22.0 by running: pip show mcp-atlassian. If installed via source, verify the commit hash is not before 5cd697d. Monitor network logs for outbound requests to unexpected internal or metadata service URLs.

Impact Analysis

An attacker could exploit this to access sensitive internal services or AWS instance metadata. This could lead to unauthorized data exposure, internal network reconnaissance, or further attacks against internal systems.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, which may violate GDPR's data protection requirements or HIPAA's safeguards for protected health information. Compliance breaches could result in legal penalties or reputational damage.

Mitigation Strategies

Upgrade mcp-atlassian to version 0.22.0 or later. Implement strict URL validation for X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers by allowlisting permitted domains or blocking private/link-local IP ranges.

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