# CVE-2024-28121

## Summary

- **CVE ID:** CVE-2024-28121
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-470
- **Published:** Mar 12, 2024
- **Last Modified:** Mar 13, 2026

## Description

stimulus_reflex is a system to extend the capabilities of both Rails and Stimulus by intercepting user interactions and passing them to Rails over real-time websockets. In affected versions more methods than expected can be called on reflex instances. Being able to call some of them has security implications. To invoke a reflex a websocket message of the following shape is sent: `\"target\":\"[class_name]#[method_name]\",\"args\":[]`. The server will proceed to instantiate `reflex` using the provided `class_name` as long as it extends `StimulusReflex::Reflex`. It then attempts to call `method_name` on the instance with the provided arguments. This is problematic as `reflex.method method_name` can be more methods that those explicitly specified by the developer in their reflex class. A good example is the instance_variable_set method. This vulnerability has been patched in versions 3.4.2 and 3.5.0.rc4. Users unable to upgrade should: see the backing GHSA advisory for mitigation advice.

## Affected Products

- stimulusreflex — stimulus_reflex (>= 3.5.0.rc1, < 3.5.0.rc4)
- stimulusreflex — stimulus_reflex (< 3.4.2)

## References

- [CNA](https://github.com/stimulusreflex/stimulus_reflex/security/advisories/GHSA-f78j-4w3g-4q65)
- [CNA](https://github.com/stimulusreflex/stimulus_reflex/commit/538582d240439aab76066c72335ea92096cd0c7f)
- [CNA](https://github.com/stimulusreflex/stimulus_reflex/blob/0211cad7d60fe96838587f159d657e44cee51b9b/app/channels/stimulus_reflex/channel.rb#L83)
- [CNA](https://github.com/stimulusreflex/stimulus_reflex/releases/tag/v3.4.2)
- [CNA](https://github.com/stimulusreflex/stimulus_reflex/releases/tag/v3.5.0.rc4)
- [CNA](http://seclists.org/fulldisclosure/2024/Mar/16)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 1.55%
- **EPSS Percentile:** 73.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._