CVE-2025-61772

7.5 HIGH 0.9% exploit odds Fix listed Denial of service Web app

What it is

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`).

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 0.9% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-10-07 15:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-19 16:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.9% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-10-07 15:16 UTC
Last modified: 2026-10-19 16:10 UTC
Exploit probability: 0.9% · EPSS, next 30 days
Weakness: CWE-400 · Uncontrolled resource consumption
Record status: Analyzed

Affected

Rack < 2.2.19
Rack < 3.1.17
Rack < 3.2.2

Attack profile CVSS 3.1 · 7.5

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-61772.md and follow it. Check whether this project is affected by CVE-2025-61772. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record