MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler
Priority LOW 27CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00262 18th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mcp-atlassian (sooperset): 0.22.0mcp-atlassian (PyPI): 0.22.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| sooperset | mcp-atlassian | before 0.22.0 | 0.22.0 | Patch available | CNA |
| — | mcp-atlassian (PyPI) | before 0.22.0 | 0.22.0 | Patch available | GHSA-g2r2-3j32-j27x |
- mcp-atlassian Vendorsooperset Affected before 0.22.0 Fixed in 0.22.0 Patch available CNA
- mcp-atlassian (PyPI) Vendor— Affected before 0.22.0 Fixed in 0.22.0 Patch available GHSA-g2r2-3j32-j27x
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* | before 0.22.0 | Vulnerable | Mcp-atlassian |
- cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* Versions before 0.22.0 Vulnerable ·Mcp-atlassian
Remediation
- Fix · CNA mcp-atlassian (sooperset) Fixed in 0.22.0
- Fix · GHSA-g2r2-3j32-j27x mcp-atlassian (PyPI) Fixed in 0.22.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-77272
- 2026-10-03 Alias added: GHSA-g2r2-3j32-j27x
References
Patch 2
More sooperset vulnerabilities
- TI-2026-53938 MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials CVSS 3.1CRITICAL 9.1
- TI-2026-53957 MCP Atlassian: SSRF Protection Bypass CVSS 4.0HIGH 8.8
- TI-2026-53935 Protection mechanism failure in sooperset mcp-atlassian CVSS 4.0HIGH 8.3
- TI-2026-53946 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
- TI-2026-53932 Path traversal in sooperset mcp-atlassian CVSS 3.1HIGH 8.6
- TI-2026-22177 Path traversal in sooperset mcp-atlassian CVSS 3.1CRITICAL 9.1
Sources
- CVE-2026-77272 · CVE Program
- CVE-2026-77272 · NVD
- FIRST EPSS
- GHSA-g2r2-3j32-j27x · GitHub Advisory Database · CC BY 4.0
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