CVE-2026-42071

Description

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. ### Impact - REPORTER (access level 25) can view file attachments that were uploaded to private bugnotes by DEVELOPER/MANAGER/ADMIN users - Private bugnotes are intended for internal developer discussion; their attachments (logs, screenshots, patches) should be equally protected - The web UI is NOT affected — it filters through bugnote_get_all_visible_bugnotes() first ### Patches - 029d9d203d9e4ae96b3e59d552fa7395cc1e5071 ### Workarounds None ### Credits Thanks to the following security researchers for independently discovering and responsibly reporting the issue. - Vishal Shukla - Tristan Madani (@TristanInSec) from Talence Security - Tang Cheuk Hei (@siunam321) This advisory's contents was largely copied from Tristan's well-written report.

How to fix CVE-2026-42071

To remediate CVE-2026-42071, upgrade the affected package to a fixed version below.

• —upgrade to 2.28.2 or later

Is CVE-2026-42071 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• >= 2.23.0, < 2.28.2

CVSS scores

References (8)

• ADVISORYgithub.com/advisories/GHSA-xjmx-cprh-646r
• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-42071
• PATCHgithub.com/mantisbt/mantisbt
• WEBgithub.com/mantisbt/mantisbt/commit/029d9d203d9e4ae96b3e59d552fa7395cc1e5071