CVE-2026-77255: high-severity vulnerability in sooperset mcp-atlassian
MCP Atlassian: Arbitrary File Read & Exfiltration (Confused Deputy) in JIRA update_issue
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.6epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Affected products
sooperset · mcp-atlassianRelated CVEs — sooperset mcp-atlassian
In the same product, most dangerous first.
CVE-2026-27826HIGHMCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headersEPSS 13.0%CVE-2026-27825CRITICALMCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachmentEPSS 11.5%CVE-2026-77254CRITICALMCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentialsEPSS 0.6%CVE-2026-77271HIGHMCP Atlassian: Incomplete path traversal fix allows intra-CWD module overwrite and RCE (bypass of CVE-2026-27825)EPSS 0.6%CVE-2026-77262HIGHMCP Atlassian: Path Traversal / Arbitrary File Read in confluence_upload_attachment MCP tool (incomplete fix of CVE-2026-27825)EPSS 0.6%CVE-2026-77243HIGHMCP Atlassian: ENABLED_TOOLS / Toolset authorization bypassEPSS 0.5%