CVE-2026-5194Network attack vector

Certificate forgery via undersized digest acceptance

Published Apr 9, 2026 · Updated Apr 9, 2026

Improper certificate validation in wolfSSL 3.12.0 through 5.9.0 allows attackers to forge certificates via undersized digests. Signature verification in wolfcrypt/src/asn.c and wolfcrypt/src/ecc.c accepts digest sizes below algorithm and key requirements and does not enforce signature OID agreement. Exposure requires certificate verification in builds with ECC plus EdDSA or ML-DSA enabled and knowledge of the public CA key; successful forgery defeats certificate-based authentication.

CVSS severity9.3
Critical
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in wolfSSL 3.12.0 through 5.9.0 allows attackers to forge certificates via undersized digests. Signature verification in wolfcrypt/src/asn.c and wolfcrypt/src/ecc.c accepts digest sizes below algorithm and key requirements and does not enforce signature OID agreement. Exposure requires certificate verification in builds with ECC plus EdDSA or ML-DSA enabled and knowledge of the public CA key; successful forgery defeats certificate-based authentication.

The record

CVE
CVE-2026-5194
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
wolfSSL
Product
wolfSSL
Classifications
CWE-295, T1557
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record 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 <5.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

wolfSSL · wolfSSLversion=3.12.0 <5.9.1

Published CVSS scores

9.3wolfSSL Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:H/SI:L/SA:L
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

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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