CVE-2023-22796Network attack vector

Service interruption via catastrophic regex backtracking

Published Feb 9, 2023 · Updated Nov 27, 2024

Regular expression denial of service in Rails Active Support before 6.1.7.1 and 7.0.0 through 7.0.4 allows attackers to interrupt service. ActiveSupport::Inflector.underscore applies a quantified uppercase group before a lookahead, allowing crafted strings to force catastrophic regex backtracking. Any application path that passes attacker-controlled text to underscore, titleize, or a dependent method can consume excessive CPU and memory until its process hangs or crashes.

CVSS severity7.5
High
EPSS probability1.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in Rails Active Support before 6.1.7.1 and 7.0.0 through 7.0.4 allows attackers to interrupt service. ActiveSupport::Inflector.underscore applies a quantified uppercase group before a lookahead, allowing crafted strings to force catastrophic regex backtracking. Any application path that passes attacker-controlled text to underscore, titleize, or a dependent method can consume excessive CPU and memory until its process hangs or crashes.

The record

CVE
CVE-2023-22796
Published
Feb 9, 2023
Updated
Nov 27, 2024
Vendor
Rails
Product
Active Support
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 27, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.1.7.1, 7.0.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rails · Active Supportversion=6.1.7.1, 7.0.4.1

Published CVSS scores

7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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