Vulnerability · Published Sep 22, 2026 · Assigned by GitHub_M
CVE-2026-77255MCP Atlassian: Arbitrary File Read & Exfiltration (Confused Deputy) in JIRA update_issue
High 8.6
In plain English
A high-severity path traversal in mcp-atlassian from sooperset. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementation without workspace validation. A caller can make the MCP server read arbitrary local files and attach them to a Jira issue, using the server as a confused deputy to exfiltrate the contents. The advisory traces the vulnerable input and processing flow through jira update_issue, attachments, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | mcp-atlassian | 0.22.0 | GHSA-2xj6-xx86-cwwc |
| PyPI | mcp-atlassian | 0.22.0 | PYSEC-2026-4080 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| sooperset | mcp-atlassian | < 0.22.0 |
Weakness: CWE-22, CWE-441 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
References
- https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc x_refsource_CONFIRM
- https://github.com/sooperset/mcp-atlassian/pull/1448 x_refsource_MISC
- https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 x_refsource_MISC
- https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 x_refsource_MISC