CVE-2026-33173

Rails Active Storage has possible content type bypass via metadata in direct uploads

Severity Score

5.3

*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

Active Storage allows users to attach cloud and local files in Rails applications. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `DirectUploadsController` accepts arbitrary metadata from the client and persists it on the blob. Because internal flags like `identified` and `analyzed` are stored in the same metadata hash, a direct-upload client can set these flags to skip MIME detection and analysis. This allows an attacker to upload arbitrary content while claiming a safe `content_type`, bypassing any validations that rely on Active Storage's automatic content type identification. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Active Storage permite a los usuarios adjuntar archivos locales y en la nube en aplicaciones Rails. Antes de las versiones 8.1.2.1, 8.0.4.1 y 7.2.3.1, 'DirectUploadsController' acepta metadatos arbitrarios del cliente y los persiste en el blob. Debido a que indicadores internos como 'identified' y 'analyzed' se almacenan en el mismo hash de metadatos, un cliente de carga directa puede establecer estos indicadores para omitir la detección y el análisis MIME. Esto permite a un atacante cargar contenido arbitrario mientras declara un 'content_type' seguro, eludiendo cualquier validación que dependa de la identificación automática del tipo de contenido de Active Storage. Las versiones 8.1.2.1, 8.0.4.1 y 7.2.3.1 contienen un parche.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

None

User Interaction

Passive

System

Vulnerable | Subsequent

Confidentiality

None

Integrity

Low

None

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2026-03-17 CVE Reserved
2026-03-23 CVE Published
2026-03-24 CVE Updated
2026-03-29 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-925: Improper Verification of Intent by Broadcast Receiver

CAPEC

References (7)

URL	Tag	Source
https://github.com/rails/rails/releases/tag/v7.2.3.1	Release Notes
https://github.com/rails/rails/releases/tag/v8.0.4.1	Release Notes
https://github.com/rails/rails/releases/tag/v8.1.2.1	Release Notes

URL	Date	SRC

URL	Date	SRC
https://github.com/rails/rails/commit/707c0f1f41f067fdf96d54e99d43b28dfaae7e53	2026-03-24
https://github.com/rails/rails/commit/8fcb934caadc79c8cc4ce53287046d0f67005b3e	2026-03-24
https://github.com/rails/rails/commit/d9502f5214e2198245a4c1defe9cd02a7c8057d0	2026-03-24

URL	Date	SRC
https://github.com/rails/rails/security/advisories/GHSA-qcfx-2mfw-w4cg	2026-03-24

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Rubyonrails Search vendor "Rubyonrails"		Rails Search vendor "Rubyonrails" for product "Rails"				< 7.2.3.1 Search vendor "Rubyonrails" for product "Rails" and version " < 7.2.3.1"		-		Affected
Rubyonrails Search vendor "Rubyonrails"		Rails Search vendor "Rubyonrails" for product "Rails"				>= 8.0.0 < 8.0.4.1 Search vendor "Rubyonrails" for product "Rails" and version " >= 8.0.0 < 8.0.4.1"		-		Affected
Rubyonrails Search vendor "Rubyonrails"		Rails Search vendor "Rubyonrails" for product "Rails"				>= 8.1.0 < 8.1.2.1 Search vendor "Rubyonrails" for product "Rails" and version " >= 8.1.0 < 8.1.2.1"		-		Affected