SSRF in Sooperset Mcp-Atlassian

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.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (62.6th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 62.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-27826: fell from 0.136 to 0.010.

EPSS over last 30 days · oldest: 0.136 · newest: 0.010 · change: -0.126

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-27826?
CVE-2026-27826 is a high-severity vulnerability in Sooperset Mcp-Atlassian, classified under Server-Side Request Forgery (SSRF). CVSS score: 8.2/10. Published 2026-03-10.
How severe is CVE-2026-27826?
High severity. CVSS v3 base score is 8.2 out of 10.