---
title: "CVE-2026-52847: MantisBT: Reflected XSS in admin/install.php"
url: https://erroneo.us/security/cve/CVE-2026-52847/
description: "CVE-2026-52847 (mantisbt/mantisbt (Composer (PHP))): MantisBT: Reflected XSS in admin/install.php"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-15
date_modified: 2026-07-15
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-52847"
kev: false
cvss: 9.2
epss: null
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-52847: MantisBT: Reflected XSS in admin/install.php

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog. That can change quickly after a public write-up; re-check if you are affected.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes mantisbt/mantisbt (Composer (PHP)) <= 2.28.3, fixed in 2.28.4 . Check your lockfile, including transitive dependencies.

## What it is

MantisBT: Reflected XSS in admin/install.php

## Affected packages

- Composer (PHP) `mantisbt/mantisbt` <= 2.28.3 → fixed: 2.28.4

## Severity

- GitHub 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`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).

## Sources

- [GitHub Advisory GHSA-77x8-3v3h-hrhv](https://github.com/advisories/GHSA-77x8-3v3h-hrhv)
- [CVE.org record CVE-2026-52847](https://www.cve.org/CVERecord?id=CVE-2026-52847)
- [NVD entry CVE-2026-52847](https://nvd.nist.gov/vuln/detail/CVE-2026-52847)
- [github.com](https://github.com/mantisbt/mantisbt/security/advisories/GHSA-77x8-3v3h-hrhv)
- [github.com](https://github.com/mantisbt/mantisbt/commit/0f32ceabadc745239754962df91a51d5d51e3fd7)
- [github.com](https://github.com/mantisbt/mantisbt/commit/f2191a0d8ce438bf74171d496cf721dae025a5c0)
- [mantisbt.org](https://mantisbt.org/bugs/view.php?id=37103)

---
Source page: https://erroneo.us/security/cve/CVE-2026-52847/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt