A missing authorization check in MantisBT's file visibility function allows any authenticated user (REPORTER+) to download attachments on private bugnotes they should not be able to access, via the REST API endpoint GET /api/rest/issues/{id}/files and SOAP API mc_issue_attachment_get endpoint.
None
Thanks to the following security researchers for independently discovering and responsibly reporting the issue.
This advisory's contents was largely copied from Tristan's well-written report.
{
"cwe_ids": [
"CWE-862"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-11T19:39:43Z",
"nvd_published_at": "2026-05-28T21:16:30Z",
"severity": "HIGH"
}