CVE-2026-33176 Rails Active Support has a possible DoS vulnerability in its number helpers
Attackers can cause denial of service in Rails applications by submitting scientific notation strings that trigger excessive resource consumption in Active Support number helpers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33176?
CVE-2026-33176 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 Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, Active Support number helpers accept strings containing scientific notation (e.g. `1e10000`), which `BigDecimal` expands into extremely large decimal representations. This can cause excessive memory allocation and CPU consumption when the expanded number is formatted, possibly resulting in a DoS vulnerability. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.
Which versions are affected by CVE-2026-33176?
6 open source packages ship an affected version, including activesupport. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
activesupport RubyGems | All versions | 7.2.3.1 |
activesupport RubyGems | All versions | 7.2.3.1 |
activesupport RubyGems | From 8.0.0.beta1 | 8.0.4.1 |
activesupport RubyGems | From 8.0.0.beta1 | 8.0.4.1 |
activesupport RubyGems | From 8.1.0.beta1 | 8.1.2.1 |
activesupport RubyGems | From 8.1.0.beta1 | 8.1.2.1 |
Products include Rubyonrails Rails.
How do I fix CVE-2026-33176?
Upgrade activesupport 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-2026-33176 being exploited?
There is no known exploitation of CVE-2026-33176 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-2026-33176, GHSA-2j26-frm8-cmj9, MINI-47qx-crvf-ffcf, MINI-jf4x-2566-cr56, MINI-rp5m-p5x3-w4rr, UBUNTU-CVE-2026-33176.