What is CVE-2026-77266?

CVE-2026-77266 is a medium-severity vulnerability in Sooperset Mcp-Atlassian, classified under Path Traversal. CVSS score: 6.5/10. Published 2026-09-22.

How severe is CVE-2026-77266?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Path Traversal in Sooperset Mcp-Atlassian

CVE-2026-77266

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.

Vulnerability class: Path Traversal (Directory Traversal)

Published 2026-09-22 · last modified 2026-09-22.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Sooperset Mcp-Atlassian — versions < 0.22.0

Weakness classification (CWE)

CWE-22 — Path Traversal

References

Frequently asked questions

What is CVE-2026-77266?: CVE-2026-77266 is a medium-severity vulnerability in Sooperset Mcp-Atlassian, classified under Path Traversal. CVSS score: 6.5/10. Published 2026-09-22.
How severe is CVE-2026-77266?: Medium severity. CVSS v3 base score is 6.5 out of 10.