CVE-2026-33169
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.
Does this matter?
Lower severity and a low EPSS score (0.50%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.50% probability · 41th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-400, CWE-1333
- Affected
- rubyonrails/rails
- Source
- security-advisories@github.com
References
- https://github.com/rails/rails/commit/29154f1097da13d48fdb3200760b3e3da66dcb11Patch
- https://github.com/rails/rails/commit/b54a4b373c6f042cab6ee2033246b1c9ecc38974Patch
- https://github.com/rails/rails/commit/ec1a0e215efd27a3b3911aae6df978a80f456a49Patch
- https://github.com/rails/rails/releases/tag/v7.2.3.1Release Notes
- https://github.com/rails/rails/releases/tag/v8.0.4.1Release Notes
- https://github.com/rails/rails/releases/tag/v8.1.2.1Release Notes
- https://github.com/rails/rails/security/advisories/GHSA-cg4j-q9v8-6v38Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.