CVE-2026-77255CWE-22CWE-441path-traversal

CVE-2026-77255

High · published September 22, 2026

CVSS v3.1
8.6
EPSS
0%
Percentile
34.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.6 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00408 · 34.0th percentile
Weaknesses
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'); CWE-441 · Unintended Proxy or Intermediary ('Confused Deputy')
Published
2026-09-22T23:16Z
Affected products (1)
ProductVersionsFixed in
mcp-atlassian/mcp_atlassian< 0.22.00.22.0
References (5)
EPSS history
Timeline
  • 24 SEP 03:25Z
    EPSS moved — → 1%
    epss
  • 22 SEP 18:29Z
    MCP Atlassian: Arbitrary File Read & Exfiltration (Confused Deputy) in JIRA update_issue
    cvelistv5