Summary
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.
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.
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
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
- 029d9d203d9e4ae96b3e59d552fa7395cc1e5071
Frequently Asked Questions
- What is CVE-2026-42071? CVE-2026-42071 is a high-severity missing authorization vulnerability in mantisbt/mantisbt (composer), affecting versions >= 2.23.0, <= 2.28.1. It is fixed in 2.28.2. The application does not perform an authorization check before performing a sensitive operation.
- Which versions of mantisbt/mantisbt are affected by CVE-2026-42071? mantisbt/mantisbt (composer) versions >= 2.23.0, <= 2.28.1 is affected.
- Is there a fix for CVE-2026-42071? Yes. CVE-2026-42071 is fixed in 2.28.2. Upgrade to this version or later.
- Is CVE-2026-42071 exploitable, and should I be worried? Whether CVE-2026-42071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-42071 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-42071? Upgrade
mantisbt/mantisbtto 2.28.2 or later.