CVE-2026-77246

MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

Published: Sep 22, 2026Updated: Sep 24, 2026 Sources: CVE List NVDCWE-22

7.4HIGH

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:AAttack Vector

Adjacent

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:CScope

Changed

Impact

C:HConfidentiality

High

I:NIntegrity

None

A:NAvailability

None

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Weaknesses

CWE-22 CWE-200 CWE-441

Affected Products

sooperset

commercialaka mcp atlassian

mcp-atlassianOn-prem

Enterprise Software / collaboration-groupware

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Collection

Discovery

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References

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j

github.com

https://github.com/sooperset/mcp-atlassian/pull/1448

github.com

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460

github.com

and 1 more references View all →

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