CVE-2023-27530Network attack vector

Service interruption via unlimited multipart part parsing

Published Mar 10, 2023 · Updated Oct 15, 2024

Denial of service in Rack before 2.0.9.3, 2.1.4.3, 2.2.6.3, or 3.0.4.2 allows remote attackers to stall multipart parsing. Rack::Multipart::Parser limits file parts but not the total number of MIME parts, so crafted requests force excessive parsing work. Any unauthenticated network client that can submit multipart/form-data can prolong request processing and interrupt application service.

CVSS severity7.5
High
EPSS probability1.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Denial of service in Rack before 2.0.9.3, 2.1.4.3, 2.2.6.3, or 3.0.4.2 allows remote attackers to stall multipart parsing. Rack::Multipart::Parser limits file parts but not the total number of MIME parts, so crafted requests force excessive parsing work. Any unauthenticated network client that can submit multipart/form-data can prolong request processing and interrupt application service.

The record

CVE
CVE-2023-27530
Published
Mar 10, 2023
Updated
Oct 15, 2024
Vendor
Rack
Product
Rack
Classifications
CWE-400, CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 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=3.0.4.2, 2.2.6.3, 2.1.4.3, 2.0.9.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rack · Rackversion=3.0.4.2, 2.2.6.3, 2.1.4.3, 2.0.9.3

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS: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-400Uncontrolled Resource Consumption
CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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