What is CVE-2026-77254?

CVE-2026-77254 is a critical-severity vulnerability in Sooperset Mcp-Atlassian, classified under Missing Authentication for Critical Function. CVSS score: 9.1/10. Published 2026-09-22.

How severe is CVE-2026-77254?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Auth bypass in Sooperset Mcp-Atlassian

CVE-2026-77254

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, requests to the HTTP MCP endpoint without a per-user identity are allowed to reach tool handlers, which then use globally configured Jira or Confluence credentials. A network caller can perform operations with the operator account's permissions unless the deployment has an independent authentication boundary. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, _get_fetcher, and global credentials, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Vulnerability class: Broken Authentication

Published 2026-09-22.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-306 — Missing Authentication for Critical Function

References

Frequently asked questions

What is CVE-2026-77254?: CVE-2026-77254 is a critical-severity vulnerability in Sooperset Mcp-Atlassian, classified under Missing Authentication for Critical Function. CVSS score: 9.1/10. Published 2026-09-22.
How severe is CVE-2026-77254?: Critical severity. CVSS v3 base score is 9.1 out of 10.