CVE-2026-77257 MCP Atlassian: HTTP upload tools accept arbitrary server-local file paths
Remote attackers can read sensitive local files and upload them as attachments via unrestricted file path parameters in MCP Atlassian server.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77257?
CVE-2026-77257 is a high-severity path traversal vulnerability in sooperset mcp-atlassian, published on 22 Sep 2026. Any signed-in user can exploit it over the 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 0.22.0, HTTP-exposed Jira and Confluence upload tools pass a caller-provided file_path to local file operations without restricting it to the workspace. A remote MCP caller with tool access can cause the server to read sensitive local files and upload them as Atlassian attachments. The advisory traces the vulnerable input and processing flow through streamable-http, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
Weakness: CWE-22
Which versions are affected by CVE-2026-77257?
3 open source packages ship an affected version, including mcp-atlassian. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mcp-atlassian PyPI | All versions | 0.22.0 |
mcp-atlassian PyPI | All versions | 0.22.0 |
mcp-atlassian PyPI | All versions | 0.22.0 |
Products include Mcp-Atlassian Mcp Atlassian.
How do I fix CVE-2026-77257?
Upgrade mcp-atlassian to 0.22.0 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-77257 being exploited?
There is no known exploitation of CVE-2026-77257 in the wild and no public exploit code.
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-2026-27825 MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment
- CVE-2026-77243 MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass
- CVE-2026-77274 MCP Atlassian: SSRF Protection Bypass
Sources
Also known as GHSA-mrq8-fv7v-hhjg, PYSEC-2026-4098.