---
id: CVE-2026-116541
title: netty-tcnative before 2.0.84.Final Denial of Service via BIO Write Overcount
summary: >-
  Netty netty-tcnative before 2.0.84.Final contains a denial of service
  vulnerability in the tcn_write_to_bytebuffer BIO write callback that
  overreports bytes consumed. Remote TLS 1.3 peers can provoke queued
  post-handshake records like Ne…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-682
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: '2026-10-26T14:59:40.847Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116541'
references:
  - url: >-
      https://github.com/netty/netty-tcnative/security/advisories/GHSA-9xr3-jwv4-r489
    label: GitHub Security Advisory (GHSA-9xr3-jwv4-r489)
  - url: >-
      https://github.com/netty/netty-tcnative/commit/e31df4a5885b35085fdfa3e2dca7c1f705d4745b
    label: Patch Commit
  - url: >-
      https://github.com/netty/netty-tcnative/blob/netty-tcnative-parent-2.0.83.Final/openssl-dynamic/src/main/c/ssl.c#L240
  - 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-tcnative-before-2.0.84-final-denial-of-service-via-bio-write-overcount
    label: >-
      VulnCheck Advisory: netty-tcnative before 2.0.84.Final Denial of Service
      via BIO Write Overcount
tags:
  - cve.org
ingestedAt: '2026-10-26T15:29:30.503Z'
---

## Overview

Netty netty-tcnative before 2.0.84.Final contains a denial of service vulnerability in the tcn_write_to_bytebuffer BIO write callback that overreports bytes consumed. Remote TLS 1.3 peers can provoke queued post-handshake records like NewSessionTicket or KeyUpdate to truncate flights, fail connections, or abort the JVM process.

## 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.