Auth bypass in Mcp-Atlassian 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 · last modified .
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
EPSS: 0.005 (45.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Mcp-Atlassian Mcp Atlassian
- Sooperset Mcp-Atlassian — versions < 0.22.0
Weakness classification (CWE)
References
- github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e… (Patch)
- github.com/sooperset/mcp-atlassian/pull/1448 (Patch, Issue Tracking)
- github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 (Release Notes)
- github.com/sooperset/mcp-atlassian/security/advisories/GHSA-3r68-hf9h-887v (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-77243?
- CVE-2026-77243 is a high-severity vulnerability in Mcp-Atlassian 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.