CVE-2026-77258

MCP Atlassian: Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path()

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment in src/mcp_atlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the workspace. A permitted Confluence MCP caller can upload the file as an attachment and disclose data readable by the server process. This issue is fixed in version 0.22.0.

Affected

sooperset · mcp-atlassian

CVSS v3.1 GITHUB

7.7 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

EPSS

0.34% chance of exploitation in the next 30 days, 26th percentile

Published

2026-09-22

Updated

2026-09-25

Proof-of-concept exploits (1)

• advisories/GHSA-93xw-j965-9mx3

Security advisories

• sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3
• sooperset/mcp-atlassian/pull/1448

References

• CVE Record
• NVD entry