Vulnerability details

CVE-2026-55872

mayerbalintdev GYM-One

GYM One admin user list is vulnerable to stored cross-site scripting

CVSS 3.1

8.7High

Official 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.

CVSS scores

Score	Version	Source	Vector
8.7High	3.1	CVEProject cvelistV5 (CNA) (GitHub_M)	`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`

Affected products

Vendor	Product	Versions	Source
mayerbalintdev	GYM-One	< 1.4.1	CVEProject cvelistV5 (CNA)

References and advisories

https://github.com/mayerbalintdev/GYM-One/commit/d3a0cf134f0ab3ac12aee7dca283b93c4290dcc4 x_refsource_MISC
https://github.com/mayerbalintdev/GYM-One/releases/tag/V1.4.1 x_refsource_MISC
https://github.com/mayerbalintdev/GYM-One/security/advisories/GHSA-75g9-vp9w-5388 x_refsource_CONFIRM

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Details

Published: 2026-10-15
Last updated: 2026-10-21
State: Published
Assigner (CNA): GitHub_M

Exploit prediction (EPSS)

0.29%

Probability of exploitation in 30 days

21.6%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: No
Exploitation: Proof of concept
Technical impact: Total

Weaknesses (CWE)

CWE-79
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')