MSRXCVE-2026-77246
CVE-2026-77246
MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path
CVSS 3.1 · CNA
chance of exploitation in the next 30 days (EPSS; higher than 40% of CVEs)
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, an HTTP transport deployment with READ_ONLY_MODE=false accepts a request without an Authorization identity and permits attacker-controlled Atlassian service headers, including X-Atlassian-Confluence-Url, to select a public attacker hostname or one allowed by MCP_ALLOWED_URL_DOMAINS. A caller can then invoke confluence_upload_attachment or the Jira attachment variant in src/mcp_atlassian/jira/attachments.py with a server-local file_path and cause the MCP process to send the file to the selected attachment endpoint. This issue is fixed in version 0.22.0.
Scores
Affected packages and fixed versions
| Package | Ecosystem | Fixed in |
|---|---|---|
| mcp-atlassian | PyPI | 0.22.0 |
Affected products
- sooperset mcp-atlassian: < 0.22.0
Weakness: CWE-22, CWE-200, CWE-441
Also known as: GHSA-wv8v-v4c5-v75j, PYSEC-2026-4104
4 references (advisories, patches, write-ups)
- https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-wv8v-v4c5-v75j · 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
Sources: CVE.org, OSV.dev, FIRST EPSS. Missing ones did not answer or have no record yet.