CVE-2026-33169: Rubyonrails Rails

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Rubyonrails Rails: before 7.2.3.1 (fixed in 7.2.3.1); from 8.0.0, before 8.0.4.1 (fixed in 8.0.4.1); from 8.1.0, before 8.1.2.1 (fixed in 8.1.2.1)

Published 2026-03-24. Last modified 2026-06-17.