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

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). 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
    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

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