{"cve":"CVE-2026-77255","nvd":{"published":"2026-09-22T19:16:49.850","modified":"2026-09-29T13:41:25.460","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","score":8.6},"cwes":["CWE-22","CWE-441"],"references":["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"],"products":["mcp-atlassian:mcp_atlassian"],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-77255","score":0.00459,"percentile":0.39802,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-2xj6-xx86-cwwc","url":"https://osv.dev/vulnerability/GHSA-2xj6-xx86-cwwc","summary":"MCP Atlassian: Arbitrary File Read & Exfiltration (Confused Deputy) in JIRA update_issue","modified":"2026-10-01T17:55:51.813579377Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]},{"id":"PYSEC-2026-4080","url":"https://osv.dev/vulnerability/PYSEC-2026-4080","summary":"MCP Atlassian: Arbitrary File Read & Exfiltration (Confused Deputy) in JIRA update_issue","modified":"2026-10-01T17:45:06.278418064Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}