Medium severity · published Mar 23, 2026
CVE-2026-33169
Rails Active Support has a possible ReDoS vulnerability in number_to_delimited
5.3
CVSS
0.7%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 51% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AC
activesupport · rails
>= 8.1.0.beta1, < 8.1.2.1; >= 8.0.0.beta1, < 8.0.4.1; < 7.2.3.1 · source: vendor
RA
Rails · Rubyonrails
before 7.2.3.1; 8.0.0 before 8.0.4.1; 8.1.0 before 8.1.2.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33169
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33169
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
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