MantisBT: Reflected XSS in admin/install.php via unescaped printf

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

MantisBT 2.28.3 and earlier contains six reflected XSS injection points in /admin/install.php. User-supplied parameters are echoed into HTML without escaping via an unescaped printf format string. No authentication is required. A Content Security Policy (script-src 'self') prevents inline JavaScript execution, but the CSP is missing a form-action directive, allowing exploitation via credential-phishing form injection and <meta open redirects. Impact - Credential phishing: Attacker crafts a URL that renders a fake login form on the real MantisBT admin page. Admin credentials are submitted to an attacker-controlled server. - Open redirect: Victim is silently redirected to a phishing or malware site. - UI manipulation: CSS injection can hide legitimate page content and overlay attacker-controlled HTML, enabling social engineering. Patches - https://github.com/mantisbt/mantisbt/commit/297773fbb238c39a153bd888431b41a176132098 Workarounds Remove the /admin directory, as recommended in the…

Published by the source

15 Jul 2026, 18:34 UTC

Last modified by the source

15 Jul 2026, 18:34 UTC

Source last checked

26 Oct 2026, 14:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vcrw-4xvv-jh49

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# Patch Next advisory brief: CVE-2026-52881

Advisory: MantisBT: Reflected XSS in admin/install.php via unescaped printf
IDs: CVE-2026-52881, GHSA-vcrw-4xvv-jh49
Record: https://patchnext.com/advisories/cve-2026-52881 (revision 1, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mantisbt/mantisbt 2.28.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist mantisbt/mantisbt: affected <= 2.28.3; fixed in 2.28.4

## Suggested inspection (read-only)
- Packagist mantisbt/mantisbt: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mantisbt/mantisbt.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vcrw-4xvv-jh49 (GitHub-reviewed advisory GHSA-vcrw-4xvv-jh49 lists affected ranges: Packagist mantisbt/mantisbt >=0 <=2.28.3)

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