CVE-2026-55872
8.7HighPublished 15 Oct 2026 · NVD status: Deferred · AI triage by gemini-3.8-flash
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
- Impact
- High impact on confidentiality, integrity
- Weakness
- CWE-79
Impact
Authenticated attackers can execute arbitrary JavaScript with full administrator privileges when an admin views the user list. This allows session hijacking or unauthorized administrative actions via stored cross-site scripting.
Root cause
The application fails to HTML-encode the firstname, lastname, and email fields before rendering them in the administrator user list.
Affected systems
GYM One prior to 1.4.1
CVSS v3.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Fix & remediation
Upgrade to GYM One version 1.4.1. If upgrading immediately is not possible, restrict access to the /admin/users/ endpoint or manually sanitize malicious records directly in the database.
$ git pull origin main && git checkout V1.4.1AI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD description
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.