CVE-2026-27826

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

CVSS v3 8.2 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 4.7

Attack Vector ADJACENT_NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/sooperset/mcp-atlassian/commit/5cd697dfce9116ef330b8dc7a91291640e0528d9	Patch
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:sooperset:mcp_atlassian:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-03-10 19:17

Updated : 2026-06-17 10:27

NVD link : CVE-2026-27826

Mitre link : CVE-2026-27826

CVE.ORG link : CVE-2026-27826

JSON object : View

Products Affected

sooperset

mcp_atlassian

CWE

CWE-918

Server-Side Request Forgery (SSRF)

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