CVE-2026-77274
Received Received - Intake

SSRF via Authority Confusion 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, validate_url_for_ssrf has a backslash authority confusion because it interprets the authority differently from the Requests connection layer in the header-based Jira and Confluence URL authentication flow. A crafted URL can validate as an external hostname while the HTTP client connects to an internal host, permitting server-side requests to protected network resources. 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-2026-77274
EUVD
EUVD-2026-84649

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-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 an SSRF (Server-Side Request Forgery) vulnerability in the mcp-atlassian package versions before 0.22.0. The validate_url_for_ssrf function incorrectly interprets URLs due to differing parsing methods between validation and HTTP requests. Attackers can craft URLs with backslashes to bypass SSRF protections and force connections to internal or loopback services.

Detection Guidance

Check the installed version of mcp-atlassian using pip show mcp-atlassian. If the version is below 0.22.0, the system is vulnerable. Monitor network traffic for unexpected internal requests originating from the mcp-atlassian service.

Impact Analysis

An attacker could exploit this to access internal network resources, bypass firewalls, or interact with services not intended to be exposed. This could lead to data theft, unauthorized actions, or further network compromise depending on the internal services targeted.

Compliance Impact

This SSRF vulnerability could lead to unauthorized access to internal systems or sensitive data, which may violate compliance requirements under GDPR (data protection) and HIPAA (healthcare data privacy). Unauthorized internal network access could expose personal or protected health information, leading to regulatory penalties or breaches of confidentiality.

Mitigation Strategies

Upgrade mcp-atlassian to version 0.22.0 or later immediately. If upgrading is not possible, disable the header-based Jira/Confluence URL authentication flow as a temporary workaround.

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