CVE-2026-27825 MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment
An attacker can write arbitrary files to any path via the download_path parameter, leading to arbitrary code execution on the MCP Atlassian server.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27825?
CVE-2026-27825 is a critical path traversal vulnerability in sooperset mcp-atlassian, published on 10 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required). Version 0.17.0 fixes the issue.
Which versions are affected by CVE-2026-27825?
3 open source packages ship an affected version, including mcp-atlassian. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mcp-atlassian PyPI | All versions | 0.17.0 |
mcp-atlassian PyPI | All versions | 0.17.0 |
mcp-atlassian PyPI | All versions | 0.17.0 |
Products include Mcp-Atlassian Mcp Atlassian.
How do I fix CVE-2026-27825?
Upgrade mcp-atlassian to 0.17.0 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-27825 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27825 exists.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in sooperset mcp-atlassian
- CVE-2026-77244 [mcp-atlassian] Authentication bypass in HTTP transport: AtlassianOpaqueTokenVerifier accepts any non-empty token
- CVE-2026-77254 MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials
- CVE-2026-77243 MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass
- CVE-2026-77274 MCP Atlassian: SSRF Protection Bypass
- CVE-2026-77248 MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport
Sources
Also known as GHSA-xjgw-4wvw-rgm4, PYSEC-2026-408.