What is CVE-2026-77243?

CVE-2026-77243 is a high-severity vulnerability in Sooperset Mcp-Atlassian, classified under Missing Authorization. CVSS score: 8.8/10. Published 2026-09-22.

How severe is CVE-2026-77243?

High severity. CVSS v3 base score is 8.8 out of 10.

Auth bypass in Sooperset Mcp-Atlassian

CVE-2026-77243

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, ENABLED_TOOLS and TOOLSETS are applied when tools are listed but are not rechecked when a tools/call request is dispatched. A client that knows a hidden tool name can directly invoke excluded read, write, or delete tools despite the operator's configured least-privilege restrictions. The advisory traces the vulnerable input and processing flow through ENABLED_TOOLS, TOOLSETS, tools/list, tools/call, and _call_tool_mcp, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Vulnerability class: Broken Access Control

Published 2026-09-22 · last modified 2026-09-22.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Sooperset Mcp-Atlassian — versions < 0.22.0

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

Frequently asked questions

What is CVE-2026-77243?: CVE-2026-77243 is a high-severity vulnerability in Sooperset Mcp-Atlassian, classified under Missing Authorization. CVSS score: 8.8/10. Published 2026-09-22.
How severe is CVE-2026-77243?: High severity. CVSS v3 base score is 8.8 out of 10.