CVE-2026-77272
MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler
- State
- Published
- Severity
- 5.4 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 error query parameter is passed to CallbackHandler._send_response in oauth_setup.py and interpolated into an HTML page without escaping. A crafted authorization callback can inject markup or script that executes in the browser of a user completing the OAuth flow. This issue is fixed in version 0.22.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.4 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N | GitHub_M |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
mcp-atlassiansooperset |
|
References
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