CVE-2026-77246

HIGH 7.4

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

CVSS Score

7.4

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-22 CWE-200 CWE-441
Vendor	sooperset
Product	mcp-atlassian
Published	Sep 22, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

Affected Versions

sooperset / mcp-atlassian

< 0.22.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: 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: https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0