CVE-2026-33169

Rails Active Support has a possible ReDoS vulnerability in number_to_delimited

MEDIUM
5.3
CVSS Score
Published: March 23, 2026 at 11:07 PM UTC
Updated: June 17, 2026 at 10:37 AM UTC
2 products affected across 2 vendorsRailsActive Support

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 7.2.3.18.0.0 ≤ v < 8.0.4.18.1.0 ≤ v < 8.1.2.1
v < 7.2.3.1v < 8.0.4.1v < 8.1.2.1
Affected range stops below 7.2.3.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.0.4.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.1.2.1, so it looks safe — our inference, not a vendor statement

References (7)

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400CWE-1333

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