CVE-2024-47889Network attack vector

Service interruption via backtracking list-marker expressions

Published Oct 16, 2024 · Updated Oct 17, 2024

Regular expression denial of service in Ruby on Rails Action Mailer allows remote attackers to interrupt applications with crafted text. The block_format helper applies two backtracking regular-expression substitutions to untrusted list-marker text instead of parsing it linearly. Reachability requires an application to pass attacker-controlled text to block_format under Ruby before 3.2; prolonged matching consumes processing time and interrupts service.

CVSS severityUnavailable
Unscored
EPSS probability0.94%
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 Action Mailer allows remote attackers to interrupt applications with crafted text. The block_format helper applies two backtracking regular-expression substitutions to untrusted list-marker text instead of parsing it linearly. Reachability requires an application to pass attacker-controlled text to block_format under Ruby before 3.2; prolonged matching consumes processing time and interrupts service.

The record

CVE
CVE-2024-47889
Published
Oct 16, 2024
Updated
Oct 17, 2024
Vendor
Rails
Product
Ruby on Rails
Classifications
CWE-1333, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 16, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=>= 3.0.0, < 6.1.7.9
  2. Affected versionversion=3.0.0 <6.1.7.9
  3. Affected versionversion=>= 7.0.0, < 7.0.8.5
  4. Affected versionversion=7.0.0 <7.0.8.5
  5. Affected versionversion=>= 7.1.0, < 7.1.4.1
  6. Affected versionversion=7.1.0 <7.1.4.1
  7. Affected versionversion=>= 7.2.0, < 7.2.1.1
  8. Affected versionversion=7.2.0 <7.2.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rails · Ruby on Railsversion=>= 3.0.0, < 6.1.7.9; version=3.0.0 <6.1.7.9; version=>= 7.0.0, < 7.0.8.5; version=7.0.0 <7.0.8.5; version=>= 7.1.0, < 7.1.4.1; version=7.1.0 <7.1.4.1; version=>= 7.2.0, < 7.2.1.1; version=7.2.0 <7.2.1.1

Published CVSS scores

6.6GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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