VYPR
← All advisories
High severityNVD Advisory· Published Oct 7, 2025· Updated Oct 7, 2025

Rack's unbounded multipart preamble buffering enables DoS (memory exhaustion)

CVE-2025-61770

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.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
rackRubyGems
< 2.2.192.2.19
rackRubyGems
>= 3.1, < 3.1.173.1.17
rackRubyGems
>= 3.2, < 3.2.23.2.2

Affected products

145

Patches

Vulnerability mechanics

References

7

News mentions

0

No linked articles in our index yet.