CVE-2026-77272

MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler

Published: Sep 22, 2026Updated: Sep 23, 2026 Sources: CVE List NVDCWE-79

5.4MEDIUM

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:RUser Interaction

Required

Scope

S:UScope

Unchanged

Impact

C:LConfidentiality

Low

I:LIntegrity

Low

A:NAvailability

None

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Weaknesses

CWE-79

Affected Products

sooperset

commercialaka mcp atlassian

mcp-atlassianOn-prem

Enterprise Software / collaboration-groupware

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Execution

Initial Access

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References

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460

github.com

https://github.com/sooperset/mcp-atlassian/pull/1448

github.com

https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0

github.com

and 1 more references View all →

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