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Rack has possible DoS Vulnerability in Multipart MIME parsing

High severity GitHub Reviewed Published Mar 8, 2023 to the GitHub Advisory Database • Updated Dec 17, 2023

Package

bundler rack (RubyGems)

Affected versions

< 2.0.9.3
>= 2.1.0, < 2.1.4.3
>= 2.2.0, < 2.2.6.3
>= 3.0.0, < 3.0.4.2

Patched versions

2.0.9.3
2.1.4.3
2.2.6.3
3.0.4.2

Description

There is a possible DoS vulnerability in the Multipart MIME parsing code in Rack. This vulnerability has been assigned the CVE identifier CVE-2023-27530.

Versions Affected: All. Not affected: None Fixed Versions: 3.0.4.2, 2.2.6.3, 2.1.4.3, 2.0.9.3

Impact

The Multipart MIME parsing code in Rack limits the number of file parts, but does not limit the total number of parts that can be uploaded. Carefully crafted requests can abuse this and cause multipart parsing to take longer than expected.

All users running an affected release should either upgrade or use one of the workarounds immediately.

Workarounds

A proxy can be configured to limit the POST body size which will mitigate this issue.

References

Published to the GitHub Advisory Database Mar 8, 2023
Reviewed Mar 8, 2023
Published by the National Vulnerability Database Mar 10, 2023
Last updated Dec 17, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

0.095%
(41st percentile)

Weaknesses

CVE ID

CVE-2023-27530

GHSA ID

GHSA-3h57-hmj3-gj3p

Source code

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