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CVE-2026-27826

CVE-2026-27826 · MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 8.2 · High · EPSS 13.0% · Public exploit · Fix available

Published
Updated

Stack: python

Affected products and versions

  • mcp-atlassian

    Versions
    • < 0.17.0: Affected

    No fix published

  • mcp-atlassian PyPI

    Versions
    • 0.1.1
    • 0.1.10
    • 0.1.11
    • 0.1.12
    • 0.1.13
    • 0.1.14
    • 0.1.15
    • 0.1.16
    • 0.1.2
    • 0.1.3
    • 0.1.4
    • 0.1.6
    • 0.1.7
    • 0.1.8
    • 0.1.9
    • 0.10.0
    • 0.10.1
    • 0.10.2
    • 0.10.3
    • 0.10.4
    • 0.10.5
    • 0.10.6
    • 0.11.0
    • 0.11.1
    • 0.11.10
    • 0.11.11
    • 0.11.12
    • 0.11.2
    • 0.11.2a2
    • 0.11.3
    • 0.11.4
    • 0.11.5
    • 0.11.6
    • 0.11.7
    • 0.11.8
    • 0.11.9
    • 0.12.0
    • 0.13.0
    • 0.13.1
    • 0.14.0
    • 0.14.1
    • 0.14.2
    • 0.14.3
    • 0.15.0
    • 0.16.0
    • 0.16.1
    • 0.2.0
    • 0.2.1
    • 0.2.2
    • 0.2.3
    • 0.2.4
    • 0.2.5
    • 0.2.6
    • 0.3.0
    • 0.3.1
    • 0.4.0
    • 0.5.0
    • 0.6.0
    • 0.6.1
    • 0.6.2
    • 0.6.3
    • 0.6.4
    • 0.6.5
    • 0.7.0
    • 0.7.1
    • 0.8.0
    • 0.8.1
    • 0.8.2
    • 0.8.3
    • 0.8.4
    • 0.9.0
    Affected ranges
    • ECOSYSTEM: < 0.17.0

    Update to 0.17.0

Original sources

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