rails activesupport prior 7.2.3.1/8.0.4.1/8.1.2.1 Regular Expression resource consumption

Summaryinfo

A vulnerability labeled as problematic has been found in rails activesupport. This issue affects some unknown processing of the component Regular Expression Handler. Executing a manipulation can lead to resource consumption. This vulnerability is tracked as CVE-2026-33169. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in rails activesupport and classified as problematic. This vulnerability affects an unknown part of the component Regular Expression Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-33169 since 03/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 7.2.3.1, 8.0.4.1 or 8.1.2.1 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 29154f1097da13d48fdb3200760b3e3da66dcb11 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1687). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• IBM License Metric Tool

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Vendor

• rails

Name

• activesupport

License

• open-source

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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