NIST deprecates RSA-2048 from 2030. Find every one of them before attackers do.
💎 RubyGems
Not in CISA KEV

Rails Active Storage has possible content type bypass via metadata in direct uploadsGHSA-qcfx-2mfw-w4cg

Fix: rails/rails@707c0f1

GHSA-qcfx-2mfw-w4cg is a CWE-925 vulnerability in activestorage. A fix is available for activestorage — see the affected versions and patch details below.

Also known asCVE-2026-33173
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-qcfx-2mfw-w4cg.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk
0.00%0.31%0.62%0.93%0.0%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

3 pkgs affected
💎activestorage💎activestorage💎activestorage

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsactivestorage≥ 8.1.0.beta1&&< 8.1.2.18.1.2.1bundle update activestorage --conservative
💎RubyGemsactivestorage≥ 8.0.0.beta1&&< 8.0.4.18.0.4.1bundle update activestorage --conservative
💎RubyGemsactivestorageall versions7.2.3.1bundle update activestorage --conservative

Affected Products

1 product · 3 configurations
Application
railsrubyonrails
≥ 8.1.0 && < 8.1.2.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for activestorage, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update activestorage to 8.1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qcfx-2mfw-w4cg is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact Active Storage's `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 malicious direct-upload client could set these flags. ### Releases The fixed releases are available at the normal locations. ### Credit This was responsible reported by Hackerone researcher [pwnie](https://hackerone.com/pwnie)
O3 Security · Impact-Aware SCA

Is GHSA-qcfx-2mfw-w4cg in your dependencies?

Find it across RubyGems, including transitive dependencies.

Scan my dependencies How O3 SCA works
Rails Active Storage has possible content type bypass via…