CVE-2025-11936Network attack vector

Server resource exhaustion via duplicate KeyShare entries

Published Nov 21, 2025 · Updated Dec 8, 2025

Improper input validation in wolfSSL 3.12.0 through 5.8.3 allows remote attackers to exhaust server resources with a TLS 1.3 ClientHello. The KeyShareEntry parser accepts repeated entries for the same supported group and allocates new key-share state without releasing the prior allocation. Only server-side TLS 1.3 processing is exposed; repeated unauthenticated handshakes consume CPU and memory until the service becomes unavailable.

CVSS severity6.3
Medium
EPSS probability0.43%
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 exhaust server resources with a TLS 1.3 ClientHello. The KeyShareEntry parser accepts repeated entries for the same supported group and allocates new key-share state without releasing the prior allocation. Only server-side TLS 1.3 processing is exposed; repeated unauthenticated handshakes consume CPU and memory until the service becomes unavailable.

The record

CVE
CVE-2025-11936
Published
Nov 21, 2025
Updated
Dec 8, 2025
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 8, 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=3.12.0 <5.8.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

wolfSSL · wolfSSLversion=3.12.0 <5.8.4

Published CVSS scores

6.3wolfSSL Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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