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VULNERABILITIES

CVE-2026-77255 Details

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementation without workspace validation. A caller can make the MCP server read arbitrary local files and attach them to a Jira issue, using the server as a confused deputy to exfiltrate the contents. The advisory traces the vulnerable input and processing flow through jira update_issue, attachments, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:8.6 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc CISA-ADPExploitVendor Advisory
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 [email protected]Patch
https://github.com/sooperset/mcp-atlassian/pull/1448 [email protected]Issue TrackingPatch
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 [email protected]Release Notes
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc [email protected]ExploitVendor Advisory

Weakness Enumeration

CWE-IDCWE NameSource
CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')[email protected]
CWE-441Unintended Proxy or Intermediary ('Confused Deputy')[email protected]

Affected Products

ProductVersions
mcp-atlassian mcp atlassian
< 0.22.0

CPE

  • cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.

Change History

3 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-77255
NVD Published Date:
Sep 22, 2026
NVD Last Modified:
Sep 29, 2026
Source:
[email protected]
CVE-2026-77255 Details - Not Deferred