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CVE-2025-61770— Rack's unbounded multipart preamble buffering enables DoS (memory exhaustion)

Quick assessment

Affected
rack rack
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Rack是Rack开源的一个模块化的Ruby web服务器界面。 Rack 2.2.19之前版本、3.1.17之前版本和3.2.2之前版本存在资源管理错误漏洞，该漏洞源于Rack::Multipart::Parser对多部分前导码无限制缓冲，可能导致内存耗尽和进程终止。

CVSS 7.5 · High EPSS 0.93% · P59

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking
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I. Basic Information for CVE-2025-61770

Vulnerability Information
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Vulnerability Title
Rack's unbounded multipart preamble buffering enables DoS (memory exhaustion)
Source: CVE Program / CVE List V5
Vulnerability 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` buffers the entire multipart preamble (bytes before the first boundary) in memory without any size limit. A client can send a large preamble followed by a valid boundary, causing significant memory use and potential process termination due to out-of-memory (OOM) conditions. Remote attackers can trigger large transient memory spikes by including a long preamble in multipart/form-data requests. The impact scales with allowed request sizes and concurrency, potentially causing worker crashes or severe slowdown due to garbage collection. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a preamble size limit (e.g., 16 KiB) or discard preamble data entirely. Workarounds include limiting total request body size at the proxy or web server level and monitoring memory and set per-process limits to prevent OOM conditions.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Rack 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Rack是Rack开源的一个模块化的Ruby web服务器界面。 Rack 2.2.19之前版本、3.1.17之前版本和3.2.2之前版本存在资源管理错误漏洞，该漏洞源于Rack::Multipart::Parser对多部分前导码无限制缓冲，可能导致内存耗尽和进程终止。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
rack rack < 2.2.19 -

II. Public POCs for CVE-2025-61770

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 6757 chars
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III. Intelligence Information for CVE-2025-61770

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Patches & Fixes for CVE-2025-61770 (3)

Vendor Advisories for CVE-2025-61770 (1)

Same Patch Batch · rack · 2025-10-07 · 3 CVEs total

CVE-2025-61772 7.5 HIGH Rack's multipart parser buffers unbounded per-part headers, enabling DoS (memory exhaustio
CVE-2025-61771 7.5 HIGH Rack's multipart parser buffers large non‑file fields entirely in memory, enabling DoS (me

IV. Related Vulnerabilities

Same product: rack
Same vendor: rack
Same weakness: CWE-400

V. Comments for CVE-2025-61770

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