CVE-2026-77272

MEDIUM CVSS 3.1: 6.1 EPSS 0.25%
Updated Sep 28, 2026
Sooperset
Parameter Value
CVSS 6.1 (MEDIUM)
Affected Versions before 0.22.0
Fixed In 0.22.0
Type CWE-79 (Cross-Site Scripting (XSS))
Vendor Sooperset
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
Required
User action required

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Mcp-Atlassian Mcp_Atlassian
cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*
— 0.22.0