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CVE-2026-33173

21
FAUCET Score

CVE-2026-33173 is a medium-severity vulnerability affecting Active Storage in Ruby on Rails applications prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1. It allows an unauthenticated attacker to bypass content type validations during direct file uploads by manipulating internal metadata flags. This enables the upload of arbitrary content while falsely claiming a safe content type, resulting in a low integrity impact. The attack complexity is low, requiring no user interaction or privileges. There is currently no evidence of active exploitation, public exploit code, or significant community discussion regarding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 7.2.3.1CPE matchmatch criteria
cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*
>= 8.0.0, < 8.0.4.1CPE matchmatch criteria
cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*
>= 8.1.0, < 8.1.2.1CPE matchmatch criteria
cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

5.3MEDIUM

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
NONE
VS Integrity
LOW
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.39%
Probability of exploitation in next 30 days
EPSS Percentile
31.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0039 is in the 19th percentile among its peer group of 23,705 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

github_advisorypatch availablevia nvd_reference
View patch
rubygemspatch availablevia ghsa
Product: activestorageFixed in: 8.1.2.1
rubygemspatch availablevia ghsa
Product: activestorageFixed in: 8.0.4.1
rubygemspatch availablevia ghsa
Product: activestorageFixed in: 7.2.3.1

Vendor Advisories (1)

rubygemsGHSA-qcfx-2mfw-w4cgmedium

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

Mar 23, 2026

References

github.com / rails/rails/commit/707c0f1f41f067fdf96d54e99d43b28dfaae7e53
Patch
github.com / rails/rails/commit/8fcb934caadc79c8cc4ce53287046d0f67005b3e
Patch
github.com / rails/rails/commit/d9502f5214e2198245a4c1defe9cd02a7c8057d0
Patch
github.com / rails/rails/releases/tag/v7.2.3.1
Release Notes
github.com / rails/rails/releases/tag/v8.0.4.1
Release Notes
github.com / rails/rails/releases/tag/v8.1.2.1
Release Notes
github.com / rails/rails/security/advisories/GHSA-qcfx-2mfw-w4cg
Vendor Advisory