CVE-2026-77272: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in sooperset mcp-atlassian
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.
AI Analysis
Technical Summary
The vulnerability in sooperset mcp-atlassian (a Model Context Protocol server for Atlassian products) is due to improper neutralization of input during web page generation (CWE-79). Specifically, the OAuth error query parameter is interpolated into an HTML page without escaping in the CallbackHandler._send_response function within oauth_setup.py. This enables an attacker to craft an authorization callback that injects markup or script, leading to cross-site scripting in the user's browser during the OAuth flow. The issue is resolved in version 0.22.0.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary scripts in the context of the user's browser session during the OAuth authorization flow. This can lead to limited confidentiality and integrity impacts such as theft of user data or session manipulation. The CVSS 3.1 base score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, no privileges required, user interaction required, and limited confidentiality and integrity impact.
Mitigation Recommendations
Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where the vulnerability is fixed. No other mitigation is indicated or required according to the available data.
CVE-2026-77272: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in sooperset mcp-atlassian
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.
CVSS v3.1
Score 5.4medium
Affected software
sooperset
mcp-atlassian
pkg:github/sooperset/mcp-atlassianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in sooperset mcp-atlassian (a Model Context Protocol server for Atlassian products) is due to improper neutralization of input during web page generation (CWE-79). Specifically, the OAuth error query parameter is interpolated into an HTML page without escaping in the CallbackHandler._send_response function within oauth_setup.py. This enables an attacker to craft an authorization callback that injects markup or script, leading to cross-site scripting in the user's browser during the OAuth flow. The issue is resolved in version 0.22.0.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary scripts in the context of the user's browser session during the OAuth authorization flow. This can lead to limited confidentiality and integrity impacts such as theft of user data or session manipulation. The CVSS 3.1 base score is 5.4 (medium severity), reflecting network attack vector, low attack complexity, no privileges required, user interaction required, and limited confidentiality and integrity impact.
Mitigation Recommendations
Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where the vulnerability is fixed. No other mitigation is indicated or required according to the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T19:14:21.330Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab2cd74f7a7c54106997ea4
Added to database: 09/22/2026, 18:48:20 UTC
Last enriched: 09/22/2026, 19:03:04 UTC
Last updated: 09/23/2026, 01:58:06 UTC
Views: 7
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