CVE-2026-33174 Rails Active Storage has a possible DoS vulnerability when in proxy mode via Range requests
Attackers can cause memory exhaustion and denial of service in Rails applications using Active Storage proxy mode by sending large Range requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33174?
CVE-2026-33174 is a medium-severity denial of service vulnerability in Rubyonrails Rails, published on 23 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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, when serving files through Active Storage's proxy delivery mode, the proxy 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. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
Weakness: CWE-789
Which versions are affected by CVE-2026-33174?
6 open source packages ship an affected version, including activestorage. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
activestorage RubyGems | All versions | 7.2.3.1 |
activestorage RubyGems | All versions | 7.2.3.1 |
activestorage RubyGems | From 8.0.0.beta1 | 8.0.4.1 |
activestorage RubyGems | From 8.0.0.beta1 | 8.0.4.1 |
activestorage RubyGems | From 8.1.0.beta1 | 8.1.2.1 |
activestorage RubyGems | From 8.1.0.beta1 | 8.1.2.1 |
Products include Rubyonrails Rails.
How do I fix CVE-2026-33174?
Upgrade activestorage to a fixed version for your release line: 7.2.3.1, 8.0.4.1 or 8.1.2.1.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-33174 being exploited?
There is no known exploitation of CVE-2026-33174 in the wild and no public exploit code.
Other vulnerabilities in Rubyonrails Rails
- CVE-2013-0277 Active Record contains deserialization of arbitrary YAML
- CVE-2017-17916 SQL injection in n/a
- CVE-2017-17917 SQL injection in n/a
- CVE-2026-33195 Rails Active Storage has possible Path Traversal in DiskService
- CVE-2024-26142 Rails possible ReDoS vulnerability in Accept header parsing in Action Dispatch
Sources
Also known as DEBIAN-CVE-2026-33174, GHSA-r46p-8f7g-vvvg, UBUNTU-CVE-2026-33174.