sooperset mcp-atlassian up to 0.21.x Attachment Upload attachments.py confluence_upload_attachment file_path improper authorization

Summaryinfo

A vulnerability has been found in sooperset mcp-atlassian up to 0.21.x and classified as problematic. Affected is the function confluence_upload_attachment of the file src/mcp_atlassian/jira/attachments.py of the component Attachment Upload. This manipulation of the argument file_path causes improper authorization. The identification of this vulnerability is CVE-2026-77246. It is possible to initiate the attack remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in sooperset mcp-atlassian up to 0.21.x and classified as problematic. Affected by this vulnerability is the function confluence_upload_attachment of the file src/mcp_atlassian/jira/attachments.py of the component Attachment Upload. The manipulation of the argument file_path with an unknown input leads to a improper authorization vulnerability. The CWE definition for the vulnerability is CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect confidentiality. The summary by CVE is:

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-77246 since 08/20/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1548.002 for this issue.

Upgrading to version 0.22.0 eliminates this vulnerability.

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Productinfo

Type

• Artificial Intelligence Software

Vendor

• sooperset

Name

• mcp-atlassian

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21

Website

• Product: https://github.com/sooperset/mcp-atlassian/

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