---
id: CVE-2026-116542
title: >-
  Netty netty-tcnative before 2.0.84.Final SNI Hostname Spoofing via Modified
  UTF-8 Decoding
summary: >-
  Netty netty-tcnative before 2.0.84.Final contains an SNI hostname spoofing
  vulnerability that allows remote unauthenticated clients to alter hostnames
  via JNI NewStringUTF decoding. Attackers can send overlong encodings like 0xC0
  0x80 in…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-176
vendor: netty
product: 'io.netty:netty-tcnative'
affected:
  - 'io.netty:netty-tcnative < 2.0.84.Final'
  - 'io.netty:netty-tcnative-boringssl-static < 2.0.84.Final'
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T14:59:41.528Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116542'
references:
  - url: >-
      https://github.com/netty/netty-tcnative/security/advisories/GHSA-2784-hxmm-4hgf
    label: GitHub Security Advisory (GHSA-2784-hxmm-4hgf)
  - url: >-
      https://github.com/netty/netty-tcnative/commit/a879c85b9776cf478aada3ca69e60b8c0a99ed38
    label: Patch Commit
  - url: >-
      https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/sslcontext.c#L2608
  - url: >-
      https://github.com/netty/netty-tcnative/releases/tag/netty-tcnative-parent-2.0.84.Final
    label: netty-tcnative netty-tcnative-parent-2.0.84.Final Release Notes
  - url: 'https://github.com/netty/netty-tcnative'
  - url: >-
      https://www.vulncheck.com/advisories/netty-netty-tcnative-before-2.0.84-final-sni-hostname-spoofing-via-modified-utf-8-decoding
    label: >-
      VulnCheck Advisory: Netty netty-tcnative before 2.0.84.Final SNI Hostname
      Spoofing via Modified UTF-8 Decoding
tags:
  - cve.org
ingestedAt: '2026-10-26T15:29:30.502Z'
---

## Overview

Netty netty-tcnative before 2.0.84.Final contains an SNI hostname spoofing vulnerability that allows remote unauthenticated clients to alter hostnames via JNI NewStringUTF decoding. Attackers can send overlong encodings like 0xC0 0x80 in the ClientHello server_name to confuse SNI-based certificate selection, access decisions, and logging.

## Affected

- `io.netty:netty-tcnative < 2.0.84.Final`
- `io.netty:netty-tcnative-boringssl-static < 2.0.84.Final`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.