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HIGH

CVE-2024-28121

CVSS v3

8.8

HIGH

EPSS Score

1.6 %

exploit probability, as of 2026-10-20

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • stimulus_reflexRubyGemsall versions · fixed in 3.4.2
  • stimulus_reflexnpmall versions · fixed in 3.4.2

Full record on NVD

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.

Technical details

Published
2024-03-12

Frequently asked questions

What is CVE-2024-28121?

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.

Is CVE-2024-28121 actively exploited?

Active exploitation of CVE-2024-28121 has not been confirmed. Its EPSS score was 1.6% on 2026-10-20, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2024-28121?

CVE-2024-28121 has a CVSS v3 base score of 8.8 (HIGH severity).

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