# 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. - **Severity:** Critical 9.1 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`) - **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:** Yes - **Published:** 10 Mar 2026 - **Updated:** 10 Mar 2026 - **Also known as:** GHSA-xjgw-4wvw-rgm4, PYSEC-2026-408 ## 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. Weakness: CWE-73 (External Control of File Name or Path), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) ## Which versions are affected by CVE-2026-27825? 3 open source packages ship an affected version, including mcp-atlassian. It affects 1 product. | Package | Ecosystem | 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: Mcp-Atlassian Mcp Atlassian. ## How do I fix CVE-2026-27825? Upgrade mcp-atlassian to 0.17.0 or later. ## 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: - Information about CVE-2026-27825 & CVE-2026-27826 discovered by Pluto Security and a bash script for identifying vulnerable mcp-atlassian instances allowing for automatic update to a fixed version. (github_poc): https://github.com/plutosecurity/MCPwnfluence ## Other vulnerabilities in sooperset mcp-atlassian - [CVE-2026-77244](https://insights.sbomify.com/CVE-2026-77244/): [mcp-atlassian] Authentication bypass in HTTP transport: AtlassianOpaqueTokenVerifier accepts any non-empty token (critical 10.0) - [CVE-2026-77254](https://insights.sbomify.com/CVE-2026-77254/): MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials (critical 9.1) - [CVE-2026-77243](https://insights.sbomify.com/CVE-2026-77243/): MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass (high 8.8) - [CVE-2026-77274](https://insights.sbomify.com/CVE-2026-77274/): MCP Atlassian: SSRF Protection Bypass (high 8.8) - [CVE-2026-77248](https://insights.sbomify.com/CVE-2026-77248/): MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport (high 8.6) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-27825 and fix it if it is affected. What it is: 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. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27825 exists. Affected packages and fixed versions: - mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0 - mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0 - mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-27825/ (Markdown: https://insights.sbomify.com/CVE-2026-27825/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27825 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27825 - OSV: https://osv.dev/vulnerability/CVE-2026-27825 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-27825/ Summaries are generated and may contain mistakes; the official description above is the record.