---
id: CVE-2026-55872
title: >-
  GYM One is open-source gym management software for fitness centers, personal
  trainers, and sports clubs
summary: >-
  GYM One is open-source gym management software for fitness centers, personal
  trainers, and sports clubs. Prior to 1.4.1, GYM One's admin/users/index.php
  renders the stored firstname, lastname, and email profile fields into the
  administra…
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N'
cwe:
  - CWE-79
vendor: mayerbalintdev
product: GYM-One
affected:
  - GYM-One < 1.4.1
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T19:17:41.303'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55872'
references:
  - url: >-
      https://github.com/mayerbalintdev/GYM-One/commit/d3a0cf134f0ab3ac12aee7dca283b93c4290dcc4
    label: security-advisories@github.com
  - url: 'https://github.com/mayerbalintdev/GYM-One/releases/tag/V1.4.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/mayerbalintdev/GYM-One/security/advisories/GHSA-75g9-vp9w-5388
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T19:25:46.436Z'
---

## Overview

GYM One is open-source gym management software for fitness centers, personal trainers, and sports clubs. Prior to 1.4.1, GYM One's admin/users/index.php renders the stored firstname, lastname, and email profile fields into the administrator user list without HTML output encoding. An attacker who can store values in those fields can cause content to execute in an administrator's browser when the administrator visits /admin/users/. The persistent script can access administrator-session data or perform actions with the administrator's privileges until the stored record is removed. This issue is fixed in version 1.4.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.