CVE-2025-11933Network attack vector

Service interruption via duplicate CKS extensions

Published Nov 21, 2025 · Updated Nov 21, 2025

Improper input validation in wolfSSL 3.12.0 through 5.8.3 allows remote attackers to leak memory via duplicate CKS extensions. TLSX_Parse omitted TLSX_CKS from its duplicate-extension rejection set, so repeated CKS entries in a TLS 1.3 ClientHello were processed and leaked allocations. The server build must include CKS support and receive the crafted handshake; repeated requests can deplete memory and interrupt the hosting process.

CVSS severity2.3
Low
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in wolfSSL 3.12.0 through 5.8.3 allows remote attackers to leak memory via duplicate CKS extensions. TLSX_Parse omitted TLSX_CKS from its duplicate-extension rejection set, so repeated CKS entries in a TLS 1.3 ClientHello were processed and leaked allocations. The server build must include CKS support and receive the crafted handshake; repeated requests can deplete memory and interrupt the hosting process.

The record

CVE
CVE-2025-11933
Published
Nov 21, 2025
Updated
Nov 21, 2025
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=v5.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

wolfSSL · wolfSSLversion=v5.8.2

Published CVSS scores

2.3wolfSSL Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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