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CVE-2026-33173— Rails Active Storage has possible content type bypass via metadata in direct uploads

Quick assessment

Affected
rails activestorage
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Rails是美国Rails团队的一套基于Ruby语言的开源Web应用框架。 Rails 8.1.2.1之前版本、8.0.4.1之前版本和7.2.3.1之前版本存在安全漏洞，该漏洞源于接受并持久化客户端任意元数据，可能导致绕过内容类型验证。

AI Predicted 8.1 Difficulty: Easy EPSS 0.43% · P35

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-33173

Vulnerability Information
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Vulnerability Title
Rails Active Storage has possible content type bypass via metadata in direct uploads
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-925
Source: CVE Program / CVE List V5
Vulnerability Title
Rails 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Rails是美国Rails团队的一套基于Ruby语言的开源Web应用框架。 Rails 8.1.2.1之前版本、8.0.4.1之前版本和7.2.3.1之前版本存在安全漏洞，该漏洞源于接受并持久化客户端任意元数据，可能导致绕过内容类型验证。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
rails activestorage >= 8.1.0.beta1, < 8.1.2.1 -

II. Public POCs for CVE-2026-33173

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III. Intelligence Information for CVE-2026-33173

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Patches & Fixes for CVE-2026-33173 (4)

Vendor Advisories for CVE-2026-33173 (1)

Vendor Pages for CVE-2026-33173 (2)

Same Patch Batch · rails · 2026-03-23 · 9 CVEs total

CVE-2026-33195 8.0 HIGH Rails Active Storage has possible Path Traversal in DiskService
CVE-2026-33167 Rails has a possible XSS vulnerability in its Action Pack debug exceptions
CVE-2026-33168 Rails has a possible XSS vulnerability in its Action View tag helpers
CVE-2026-33170 Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
CVE-2026-33176 Rails Active Support has a possible DoS vulnerability in its number helpers
CVE-2026-33174 Rails Active Storage has a possible DoS vulnerability when in proxy mode via Range request
CVE-2026-33169 Rails Active Support has a possible ReDoS vulnerability in number_to_delimited
CVE-2026-33202 Rails Active Storage has possible glob injection in its DiskService

IV. Related Vulnerabilities

Same product: activestorage
Same vendor: rails
Same weakness: CWE-925

V. Comments for CVE-2026-33173

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