Tracking: CVE-2026-77266
Severity: Medium
Who is affected
mcp-atlassian before 0.22.0. Exploitation requires access to an affected Jira or Confluence upload operation and a readable file on the MCP host.
How the attack works
The report identifies attachment-upload code that opens local paths without the containment checks protecting downloads. Earlier path hardening, tracked separately as GHSA-xjgw-4wvw-rgm4, did not fully protect this direction of file transfer.
An authenticated caller can supply a path outside the allowed directory and have the MCP server read it for upload. Secrets become exposed to the destination and anyone able to access that attachment.
What to do
- Upgrade to 0.22.0 or later, even if the deployment already received the earlier download-path fix.
- Audit both upload and download operations. Confirm that each operation validates the resolved local path before opening a file.
- Review attachment history for unexpected host files and revoke any credentials that were transferred.
Scope and limits
This is another report of the overlapping upload-validation problem. A previous path-traversal fix should not be treated as coverage for every file operation.