CVE-2026-77255
8.6
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Exploitability: 3.9 / Impact: 4.0
Source: security-advisories@github.com (Secondary)
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.
Affected (1)
Products: Mcp Atlassian: Mcp Atlassian
Configuration A
| Vulnerable Software | Affected Versions |
|---|---|
| version < 0.22.0 |
Related CWEs
CWE-22
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CWE-441
Unintended Proxy or Intermediary ('Confused Deputy')
The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere. This causes the product to appear to be the source of the request, leading it to act as a proxy or other intermediary between the upstream component and the external actor.
References (5)
Source: security-advisories@github.com
Patch
Source: security-advisories@github.com
Issue TrackingPatch
Source: security-advisories@github.com
Release Notes
Source: security-advisories@github.com
ExploitVendor Advisory
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
ExploitVendor Advisory
Timeline
No history available yet.