CVE-2026-5194: wolfSSL ECDSA Certificate Verification

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.6%

Up from 0.3% on 22 Oct 2026.

EPSS score, percentile 47.2 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

9.3 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• from 3.12.0 to before 5.9.1

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Advisories and patches

• github.com (Patch)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Versions not listed are: unaffected.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

Missing hash/digest size and OID checks allow digests smaller than allowed when verifying ECDSA certificates, or smaller than is appropriate for the relevant key type, to be accepted by signature verification functions. This could lead to reduced security of ECDSA certificate-based authentication if the public CA key used is also known. This affects ECDSA/ECC verification when EdDSA or ML-DSA is…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-5194 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 9 Apr 2026.
• The CVE record carries a CVSS v4.0 base score of 9.3 (Critical), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.6% (percentile 47.2), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact total.
• The credits in the CVE record name Anthropic (Claude) as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

wolfSSL ECDSA Certificate Verification

Missing hash/digest size and OID checks allow digests smaller than allowed when verifying ECDSA certificates, or smaller than is appropriate for the relevant key type, to be accepted by signature verification functions. This could lead to reduced security of ECDSA certificate-based authentication if the public CA key used is also known. This affects ECDSA/ECC verification when EdDSA or ML-DSA is also enabled.

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline