{"id":"GHSA-6cr4-ccf3-x7h4","summary":"MCP Atlassian: Arbitrary file read via confluence_upload_attachment allows exfiltration of server credentials","details":"### Summary\n\nMissing path validation in `confluence_upload_attachment` allows any authenticated MCP client to read arbitrary files from the server filesystem and exfiltrate their contents to Confluence. On Linux deployments, `/proc/self/environ` yields all runtime secrets in a single call.\n\n---\n### Details\n\n`AttachmentsMixin.upload_attachment()` in `src/mcp_atlassian/confluence/attachments.py` opens the caller-supplied `file_path` with no boundary check:\n\n```python\n# line 477\nfiles = {\"file\": (filename, open(file_path, \"rb\"))}\n```\nThe download path was correctly hardened in GHSA-xjgw-4wvw-rgm4 via `validate_safe_path()` (lines 223, 272). That fix was not applied to the upload path, leaving it completely unguarded. The MCP tool layer (`servers/confluence.py:1295`) passes `file_path` verbatim with no additional sanitization.\n\n---\n### PoC\n\n```bash\n# 1. Prepare target file (macOS demo; on Linux use /proc/self/environ directly)\ncp ~/.aws/credentials /tmp/diagram.png\n\n# 2. Call the MCP tool\nconfluence_upload_attachment(\n    content_id = \"\u003cany page attacker can edit\u003e\",\n    file_path  = \"/tmp/diagram.png\"\n)\n\n# 3. Download attachment from Confluence — contains raw credentials\n```\nTested on mcp-atlassian 0.21.1 against live Confluence Cloud. Attachment confirmed uploaded and retrieved with full credential content intact.\n\n---\n### Impact\nAny MCP client with edit access to one Confluence page can read arbitrary files from the server process. On shared/Docker deployments, `/proc/self/environ` exposes all users' API tokens in a single request. Exfiltrated Atlassian tokens provide persistent API access independent of MCP, surviving server shutdown or patching.\n\nIncomplete fix of GHSA-xjgw-4wvw-rgm4 — arbitrary file read on upload mirrors the arbitrary file write on download fixed in that advisory.\n\n\n---\n### Suggested Fix\n\n```python\n# src/mcp_atlassian/confluence/attachments.py — upload_attachment()\n# Add after abspath conversion, before open():\n\ntry:\n    validate_safe_path(file_path)\nexcept ValueError as e:\n    return {\"success\": False, \"error\": str(e)}\n```\n\nSame fix required in `upload_attachments()` and `src/mcp_atlassian/jira/attachments.py`.","aliases":["CVE-2026-77259"],"modified":"2026-09-22T21:00:04.886094188Z","published":"2026-09-22T20:35:16Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-22","CWE-552"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-09-22T20:35:16Z"},"references":[{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-6cr4-ccf3-x7h4"},{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/pull/1448"},{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"},{"type":"PACKAGE","url":"https://github.com/sooperset/mcp-atlassian"},{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"}],"affected":[{"package":{"name":"mcp-atlassian","ecosystem":"PyPI","purl":"pkg:pypi/mcp-atlassian"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0"}]}],"versions":["0.1.1","0.1.10","0.1.11","0.1.12","0.1.13","0.1.14","0.1.15","0.1.16","0.1.2","0.1.3","0.1.4","0.1.6","0.1.7","0.1.8","0.1.9","0.10.0","0.10.1","0.10.2","0.10.3","0.10.4","0.10.5","0.10.6","0.11.0","0.11.1","0.11.10","0.11.11","0.11.12","0.11.2","0.11.2a2","0.11.3","0.11.4","0.11.5","0.11.6","0.11.7","0.11.8","0.11.9","0.12.0","0.13.0","0.13.1","0.14.0","0.14.1","0.14.2","0.14.3","0.15.0","0.16.0","0.16.1","0.17.0","0.18.0","0.18.1","0.19.0","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.2.5","0.2.6","0.20.0","0.20.1","0.21.0","0.21.1","0.3.0","0.3.1","0.4.0","0.5.0","0.6.0","0.6.1","0.6.2","0.6.3","0.6.4","0.6.5","0.7.0","0.7.1","0.8.0","0.8.1","0.8.2","0.8.3","0.8.4","0.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-6cr4-ccf3-x7h4/GHSA-6cr4-ccf3-x7h4.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"}]}