VulnerabilityAnalyzed

CVE-2026-77248

An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents.

HIGH 8.6EPSS 0.47%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.47%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the streamable HTTP transport accepts requests without a user identity and falls back to operator credentials, while upload_attachment accepts an unrestricted file_path. An unauthenticated network caller can read files available to the MCP process, upload them to an attacker-selected Jira issue or Confluence page, and retrieve the contents. The advisory traces the vulnerable input and processing flow through streamable-http, UserTokenMiddleware, upload_attachment, file_path, and _get_fetcher, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS 3.1: 8.6 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
EPSS: 0.47% probability · 41th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-22, CWE-306
Affected: mcp-atlassian/mcp atlassian
Source: security-advisories@github.com

EPSS trend

EPSS moved from 0.5% on 23 September 2026 to 0.5% on 26 October 2026.

References

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460Patch
https://github.com/sooperset/mcp-atlassian/pull/1448Issue Tracking, Patch
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0Release Notes
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-cc5h-2pwp-pvccVendor Advisory
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-cc5h-2pwp-pvccVendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.