CVE-2024-26142Network attack vector

Service interruption via Accept header regex backtracking

Published Feb 27, 2024 · Updated Feb 13, 2025

Regular expression denial of service in Ruby on Rails 7.1.0 through 7.1.3 allows remote attackers to interrupt service via an Accept header. Action Dispatch's Mime::Type.parse applies a parameter-separator expression with optional leading whitespace to untrusted header text, causing excessive backtracking. An unauthenticated HTTP request can consume excessive CPU during parsing, but applications using Ruby 3.2 or newer are unaffected.

CVSS severity7.5
High
EPSS probability1.50%
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 Ruby on Rails 7.1.0 through 7.1.3 allows remote attackers to interrupt service via an Accept header. Action Dispatch's Mime::Type.parse applies a parameter-separator expression with optional leading whitespace to untrusted header text, causing excessive backtracking. An unauthenticated HTTP request can consume excessive CPU during parsing, but applications using Ruby 3.2 or newer are unaffected.

The record

CVE
CVE-2024-26142
Published
Feb 27, 2024
Updated
Feb 13, 2025
Vendor
Rails
Product
Ruby on Rails
Classifications
CWE-1333, CAPEC-492, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=>= 7.1.0, < 7.1.3.1
  2. Affected versionversion=7.1.0 <=7.1.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rails · Ruby on Railsversion=>= 7.1.0, < 7.1.3.1; version=7.1.0 <=7.1.3.1

Published CVSS scores

7.5GitHub, Inc.CVSS: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
CAPEC-492Regular Expression Exponential Blowup
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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