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Description

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.

PUBLISHED Reserved 2026-02-24 | Published 2026-03-10 | Updated 2026-03-10 | Assigner GitHub_M




HIGH: 8.2CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

Problem types

CWE-918: Server-Side Request Forgery (SSRF)

Product status

< 0.17.0
affected

References

github.com/...assian/security/advisories/GHSA-7r34-79r5-rcc9

github.com/...ommit/5cd697dfce9116ef330b8dc7a91291640e0528d9

cve.org (CVE-2026-27826)

nvd.nist.gov (CVE-2026-27826)

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