Tracking: CVE-2026-77259
Severity: High
Who is affected
mcp-atlassian before 0.22.0. The reported caller has MCP access and permission to edit the destination Confluence page.
How the attack works
The attachment-upload operation reads a caller-selected local path without the safe-path validation already present in related download code. Files outside the intended directory can be transferred to Confluence under the MCP service's identity.
A successful transfer can expose credentials or private data to the page's readers. Stopping the MCP server or patching it does not invalidate credentials already copied into an attachment.
What to do
- Upgrade to 0.22.0 or later and restart the affected process.
- Review Confluence attachments and tool activity for local paths outside the allowed directory. Preserve suspicious attachment metadata for investigation.
- Delete unauthorized copies after preserving evidence, restrict access to exposed pages, and revoke any transferred tokens or keys.
Scope and limits
The impact established here is file reading and exfiltration through uploads. A separate historical file-write issue should not be attributed to this CVE.