CVE-2025-61772

Published Oct 7, 2025

Last updated a year ago

CVSS high 7.5

Overview

Description
Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, `Rack::Multipart::Parser` can accumulate unbounded data when a multipart part’s header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`).
Source
security-advisories@github.com
NVD status
Analyzed
Products
rack

Risk scores

CVSS 3.1

Type
Secondary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
HIGH

Weaknesses

security-advisories@github.com
CWE-400

Social media

Hype score
Not currently trending

  1. 🚨 CVE-2025-61772: Malformed multipart uploads let remote actors fill Rack’s memory until your Ruby app crashes. Patch to 2.2.19 / 3.1.17 / 3.2.2 or limit request size. Details: https://t.co/BRndYemaBe #infosec #Ruby #DevOps

    @VolerionSec

    7 Oct 2025

    19 Impressions

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    0 Replies

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Configurations

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References

Sources include official advisories and independent security research.