CVE-2026-27826

8.2 HIGH 14% exploit odds Fix listed Disclosure Server

What it is

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.

At a glance

Exploitability: Can be exploited from the same network segment without logging in. High risk of data exposure.
Exploit odds: 13.9% chance of exploitation in the next 30 days (EPSS). Higher than most.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-03-10 19:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 10:27 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 13.9% in the next 30 days (EPSS).
Severity: 8.2 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-03-10 19:17 UTC
Last modified: 2026-06-17 10:27 UTC
Exploit probability: 13.9% · EPSS, next 30 days
Weakness: CWE-918 · Server-side request forgery
Record status: Analyzed

Affected

Sooperset Mcp Atlassian < 0.17.0

Attack profile CVSS 3.1 · 8.2

Attack vector: Adjacent network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Changed
Confidentiality: High
Integrity: Low
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-27826.md and follow it. Check whether this project is affected by CVE-2026-27826. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record