CVE-2026-33174: Rails Active Storage has a possible DoS vulnerability when in proxy mode via Range requests

CVE-2026-33174 · Severity: medium · CVSS 4 · Published 2026-03-23

### Impact When serving files through Active Storage's `Blobs::ProxyController`, the controller loads the entire requested byte range into memory before sending it. A request with a large or unbounded Range header (e.g. `bytes=0-`) could cause the server to allocate memory proportional to the file size, possibly resulting in a DoS vulnerability through memory exhaustion.

### Releases The fixed releases are available at the normal locations.

### Credit This issue was responsibly reported by Hackerone user [pirikara](https://hackerone.com/pirikara)

Technologies: activestorage (RubyGems). Vendors: RubyGems.

Quick answers

Is CVE-2026-33174 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-33174 being exploited in the wild.
How severe is CVE-2026-33174?
Medium severity, with a CVSS score of 4, published 23 March 2026.
Which products and versions are affected?
activestorage (RubyGems) ECOSYSTEM:introduced=8.1.0.beta1,fixed=8.1.2.1.
Is there a fix for CVE-2026-33174?
Yes. activestorage (RubyGems): upgrade to 8.1.2.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-33174?
Check whether you run activestorage (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • activestorage (RubyGems): upgrade to 8.1.2.1 or later
    bundle update activestorage

Affected products

  • activestorage (RubyGems) ECOSYSTEM:introduced=8.1.0.beta1,fixed=8.1.2.1

Identifiers

  • CVE-2026-33174
  • GHSA-r46p-8f7g-vvvg

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.