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

Quick assessment

Affected
sooperset mcp-atlassian
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

MCP Atlassian是Hyeonsoo Lee个人开发者的一个连接AI助手与项目管理工具的MCP服务器。 MCP Atlassian 0.17.0之前版本存在代码问题漏洞，该漏洞源于HTTP中间件和依赖注入层存在缺陷，可能导致未经身份验证的攻击者强制服务器进程向任意攻击者控制的URL发出出站HTTP请求。

CVSS 8.2 · High EPSS 1.04% · P63

Public Exploits 1

Nuclei · 1 CVE-2026-27826.yaml [template]
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I. Basic Information for CVE-2026-27826

Vulnerability Information
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Vulnerability Title
MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
MCP Atlassian 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
MCP Atlassian是Hyeonsoo Lee个人开发者的一个连接AI助手与项目管理工具的MCP服务器。 MCP Atlassian 0.17.0之前版本存在代码问题漏洞，该漏洞源于HTTP中间件和依赖注入层存在缺陷，可能导致未经身份验证的攻击者强制服务器进程向任意攻击者控制的URL发出出站HTTP请求。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
sooperset mcp-atlassian < 0.17.0 -

II. Public POCs for CVE-2026-27826

# POC Description Source Link Shenlong Link
1 MCP Atlassian < 0.17.0 contains a server-side request forgery caused by improper validation of custom HTTP headers in the HTTP middleware, letting unauthenticated attackers force outbound requests to arbitrary URLs, exploit requires access to the mcp-atlassian HTTP endpoint. https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-27826.yaml POC Details
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III. Intelligence Information for CVE-2026-27826

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Patches & Fixes for CVE-2026-27826 (1)

Vendor Advisories for CVE-2026-27826 (1)

IV. Related Vulnerabilities

Same product: mcp-atlassian
Same vendor: sooperset
Same weakness: CWE-918

V. Comments for CVE-2026-27826

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