CVE-2026-77268
MCP Atlassian: Insecure File Permissions on OAuth Token Storage
- State
- Published
- Severity
- 5.5 Medium
- Published
- Sep 22, 2026
- Updated
- Sep 23, 2026
- Reserved
- Aug 20, 2026
Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth fallback token directory and JSON file are created without explicit owner-only modes. Local users or processes with access through the resulting group or world permission bits can read access and refresh tokens and reuse the associated Atlassian session. The advisory traces the vulnerable input and processing flow through ~/.mcp-atlassian, oauth-<client_id>.json, access_token, and refresh_token, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.5 Medium | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N | GitHub_M |
Weaknesses
- CWE-732 Incorrect Permission Assignment for Critical Resource
Affected Products
| Product | Versions |
|---|---|
mcp-atlassiansooperset |
|
References
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