CVE-2026-33169

low-risk
Published 2026-03-24

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. `NumberToDelimitedConverter` uses a lookahead-based regular expression with `gsub!` to insert thousands delimiters. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, the interaction between the repeated lookahead group and `gsub!` can produce quadratic time complexity on long digit strings. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Do I need to act?

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0.02% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10 Medium
NETWORK / LOW complexity

Affected Products (1)

Affected Vendors

Rubyonrails

References (7)

Patch https://github.com/rails/rails/commit/29154f1097da13d48fdb3200760b3e3da66dcb11
Patch https://github.com/rails/rails/commit/b54a4b373c6f042cab6ee2033246b1c9ecc38974
Patch https://github.com/rails/rails/commit/ec1a0e215efd27a3b3911aae6df978a80f456a49
Release Notes https://github.com/rails/rails/releases/tag/v7.2.3.1
Release Notes https://github.com/rails/rails/releases/tag/v8.0.4.1
Release Notes https://github.com/rails/rails/releases/tag/v8.1.2.1
Vendor Advisory https://github.com/rails/rails/security/advisories/GHSA-cg4j-q9v8-6v38
26
/ 100
low-risk
Severity 21/34 · High
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal