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Vulnerability record · CVE-2026-77255 · published 22 September 2026

CVE-2026-77255: Path traversal vulnerability

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.

8.6 CVSS 3.1 High EPSS 0.40% · top 68.2% CWE-22 · Path traversalCWE-441 · CWE-441 Undergoing Analysis
8.6CVSS 3.1 base score
0.40%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
26 Sep 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

References

LinkTags
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
https://github.com/sooperset/mcp-atlassian/pull/1448
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-2xj6-xx86-cwwc

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Source: NIST National Vulnerability Database (record CVE-2026-77255), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.