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Vulnerabilities

Vulnerability · CVE-2026-55872

GYM One is open-source gym management software for fitness centers, personal trainers, and sports clubs.

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · GYM-One

Check if you run it

No confirmed exploitation is on record for CVE-2026-55872. EPSS is 0.23%. Act only if a listed version of GYM-One is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.23%
Remediation
Advisory link
Affected products
vendor mayerbalintdev GYM-One

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor mayerbalintdev GYM-Oneversion unspecified

How to fix CVE-2026-55872

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-55872. EPSS is 0.23%. Act only if a listed version of GYM-One is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.23%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · NIST NVD

    Detected

    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 ad

Sources

  • CVE.orgVulnerability recordCVE-2026-55872

    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.

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-55872

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-55872

    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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.