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.
https://github.com/rails/rails/security/advisories/GHSA-cg4j-q9v8-6v38
https://github.com/rails/rails/releases/tag/v8.1.2.1
https://github.com/rails/rails/releases/tag/v8.0.4.1
https://github.com/rails/rails/releases/tag/v7.2.3.1
https://github.com/rails/rails/commit/ec1a0e215efd27a3b3911aae6df978a80f456a49
https://github.com/rails/rails/commit/b54a4b373c6f042cab6ee2033246b1c9ecc38974
https://github.com/rails/rails/commit/29154f1097da13d48fdb3200760b3e3da66dcb11
Published: 2026-03-24
Updated: 2026-03-24
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Severity: Medium
Base Score: 6.9
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00016