CVE intelligence and bounded remediation
CVE-2024-21647 — Puma is a web server for Ruby/Rack applications built for parallelism
Puma is a web server for Ruby/Rack applications built for parallelism. Prior to version 6.4.2, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies in a way that allowed HTTP request smuggling. Fixed versions limits the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption. This vulnerability has been fixed in versions 6.4.2 and 5.6.8.
- Severity
- High
- CVSS
- 7.5 (3.1)
- Published
- 2024-01-08
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-444
Affected products
- puma / puma
Showing 1 representative product identities from 2 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.
Matched remediation archetype
HTTP request smuggling and message-boundary ambiguity
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Check exposure
- Inventory every proxy, CDN, gateway, load balancer, service mesh, and application server hop on affected request paths.
- Compare documented parsing and normalization behavior for message length, transfer coding, duplicate headers, and protocol translation.
- Identify connection reuse and which downstream services trust headers added by intermediaries.
Remediate safely
- Update affected intermediaries and origin servers and align them on a single standards-compliant request framing policy.
- Reject ambiguous length, transfer-coding, duplicate, malformed, and unsupported framing before forwarding.
- Normalize or remove hop-by-hop and identity headers at one controlled boundary and add multi-hop regression tests.
Authoritative sources
Complete CVE record and remediation plan
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