CVE intelligence and bounded remediation

CVE-2021-43797 — Netty Netty security vulnerability

Medium CVSS 6.5

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself. Users should upgrade to version 4.1.71.Final.

Severity
Medium
CVSS
6.5 (3.1)
Published
2021-12-09
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-444

Affected products

  • netty / netty
  • quarkus / quarkus
  • netapp / oncommand_workflow_automation
  • netapp / snapcenter
  • oracle / banking_deposits_and_lines_of_credit_servicing / 2.7
  • oracle / banking_party_management / 2.7.0

Showing 6 representative product identities from 22 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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