How severe is CVE-2021-3336?

CVE-2021-3336 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-3336 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3336?

CVE-2021-3336 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3336?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-3336 published?

CVE-2021-3336 was published on 2021-01-29 and last updated on 2026-06-17.

CVE-2021-3336

CVE-2021-3336 is a high-severity vulnerability in Wolfssl with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 6.8
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Wolfssl
Published: 2021-01-29
Last modified: 2026-06-17

Description

DoTls13CertificateVerify in tls13.c in wolfSSL before 4.7.0 does not cease processing for certain anomalous peer behavior (sending an ED22519, ED448, ECC, or RSA signature without the corresponding certificate). The client side is affected because man-in-the-middle attackers can impersonate TLS 1.3 servers.

Frequently asked questions

What is CVE-2021-3336?: DoTls13CertificateVerify in tls13.c in wolfSSL before 4.7.0 does not cease processing for certain anomalous peer behavior (sending an ED22519, ED448, ECC, or RSA signature without the corresponding certificate). The client side is affected because man-in-the-middle attackers can impersonate TLS 1.3 servers.
How severe is CVE-2021-3336?: CVE-2021-3336 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-3336 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3336?: CVE-2021-3336 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3336?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-3336 published?: CVE-2021-3336 was published on 2021-01-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

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