---
id: CVE-2025-11933
title: >-
  Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL
  5.8.2 and earlier on multiple platforms allows a remote unauthenticated
  attacker to potentially cause a denial-of-service via a crafted ClientHello
  message with du…
summary: >-
  Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL
  5.8.2 and earlier on multiple platforms allows a remote unauthenticated
  attacker to potentially cause a denial-of-service via a crafted ClientHello
  message with du…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-20
vendor: wolfssl
product: wolfssl
affected:
  - 'wolfssl >= 5.8.2, < 5.8.4'
patched:
  - wolfssl 5.8.4
published: '2025-11-21'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T10:10:00.227'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-11933'
references:
  - url: 'https://github.com/wolfSSL/wolfssl'
    label: facts@wolfssl.com
  - url: 'https://github.com/wolfSSL/wolfssl/pull/9132'
    label: facts@wolfssl.com
tags:
  - nvd
epss: 0.00421
epssPercentile: 0.34402
ingestedAt: '2026-10-08T10:28:20.695Z'
---

## Overview

Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL 5.8.2 and earlier on multiple platforms allows a remote unauthenticated attacker to potentially cause a denial-of-service via a crafted ClientHello message with duplicate CKS extensions.

## Affected

- `wolfssl >= 5.8.2, < 5.8.4`

## Remediation

Upgrade past the affected range:

- `wolfssl 5.8.4`