CVE-2026-77266

MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read and exfiltration via MCP tool call

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment accepts absolute paths and traversal sequences without constraining the resolved path to the server workspace. An MCP caller with attachment access can read a chosen server-local file and exfiltrate it through Jira or Confluence. The advisory traces the vulnerable input and processing flow through upload_attachment, file_path, and path traversal, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Affected

sooperset · mcp-atlassian

CVSS v3.1 GITHUB

6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS

0.44% chance of exploitation in the next 30 days, 37th percentile

Published

2026-09-22

Proof-of-concept exploits (1)

• advisories/GHSA-mfv2-4wvm-9pgp

Security advisories

• sooperset/mcp-atlassian/security/advisories/GHSA-mfv2-4wvm-9pgp
• sooperset/mcp-atlassian/pull/1448

References

• CVE Record
• NVD entry