# CVE-2026-33176: Rails Active Support has a possible DoS vulnerability in its number helpers

Source: https://junglewise.ai/threats/cve-2026-33176-rails-active-support-has-a-possible-dos-vulnerability-in-its  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-23. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-33176 · Severity: medium · CVSS 4 · Published 2026-03-23

### Impact
Active Support number helpers accept strings containing scientific notation (e.g. `1e10000`), which when converted to a string could be expanded 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.

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

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

Technologies: [activesupport (RubyGems)](https://junglewise.ai/threats/technologies/activesupport). Vendors: [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-33176 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33176 being exploited in the wild.

**How severe is CVE-2026-33176?** Medium severity, with a CVSS score of 4, published 23 March 2026.

**Which products and versions are affected?** activesupport (RubyGems) ECOSYSTEM:introduced=8.1.0.beta1,fixed=8.1.2.1.

**Is there a fix for CVE-2026-33176?** Yes. activesupport (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-2026-33176?** Check whether you run activesupport (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

- activesupport (RubyGems): upgrade to 8.1.2.1 or later

  ```sh
  bundle update activesupport
  ```


## Affected products

- activesupport (RubyGems) ECOSYSTEM:introduced=8.1.0.beta1,fixed=8.1.2.1

## Identifiers

- CVE-2026-33176
- GHSA-2j26-frm8-cmj9

## References

- [https://github.com/rails/rails/security/advisories/GHSA-2j26-frm8-cmj9](https://github.com/rails/rails/security/advisories/GHSA-2j26-frm8-cmj9)
- [https://github.com/rails/rails/commit/19dbab51ca086a657bb86458042bc44314916bcb](https://github.com/rails/rails/commit/19dbab51ca086a657bb86458042bc44314916bcb)
- [https://github.com/rails/rails/commit/ebd6be18120d1136511eb516338e27af25ac0a1a](https://github.com/rails/rails/commit/ebd6be18120d1136511eb516338e27af25ac0a1a)
- [https://github.com/rails/rails/commit/ee2c59e730e5b8faed502cd2c573109df093f856](https://github.com/rails/rails/commit/ee2c59e730e5b8faed502cd2c573109df093f856)
- [https://github.com/rails/rails/releases/tag/v7.2.3.1](https://github.com/rails/rails/releases/tag/v7.2.3.1)
- [https://github.com/rails/rails/releases/tag/v8.0.4.1](https://github.com/rails/rails/releases/tag/v8.0.4.1)

## Related threats

- [Rails Active Support regular expression injection in safe_constantize](https://junglewise.ai/threats/cve-2026-126080-active-support-is-a-collection-of-utility-classes-and-standard)
- [Rails Active Support MessagePack unsafe serialization XSS](https://junglewise.ai/threats/cve-2026-126075-active-support-is-a-collection-of-utility-classes-and-standard)
- [Ruby on Rails Active Support XSS in SafeBuffer](https://junglewise.ai/threats/cve-2026-33170-ruby-on-rails-active-support-xss-in-safebuffer)
- [Rails Active Support has a possible ReDoS vulnerability in number_to_delimited](https://junglewise.ai/threats/cve-2026-33169-rails-active-support-has-a-possible-redos-vulnerability-in-number)
- [Active Support Possibly Discloses Locally Encrypted Files](https://junglewise.ai/threats/cve-2023-38037-active-support-possibly-discloses-locally-encrypted-files)