Paper/Archive/CVE-2026-77254

CVE-2026-77254

sooperset mcp-atlassian — MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials

EPSS 0.6%public exploit CVSS 9.1

critical.is priorityof 100

CVSS 9.1 (CNA)9.1 / 10 × 3027.3 Not in CISA KEV+300.0 EPSS percentile 49.7.497 × 209.9 Exploit: SSVC poc+1010.0 SSVC exploitation: poc+100.0

Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource

mcp-atlassian< 0.22.0–CNA

Scores by source

GitHub_M (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitgithub.com/sooperset/mcp-atlassian/security/advisories/GHSA-vc8m-84rp-53hx refgithub.com/sooperset/mcp-atlassian/pull/1448 refgithub.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 refgithub.com/sooperset/mcp-atlassian/releases/tag/v0.22.0