How severe is CVE-2021-37155?

CVE-2021-37155 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-37155 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-37155?

CVE-2021-37155 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-37155?

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

When was CVE-2021-37155 published?

CVE-2021-37155 was published on 2021-07-21 and last updated on 2026-06-17.

CVE-2021-37155

CVE-2021-37155 is a critical-severity vulnerability in Wolfssl with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Wolfssl
Published: 2021-07-21
Last modified: 2026-06-17

Description

wolfSSL 4.6.x through 4.7.x before 4.8.0 does not produce a failure outcome when the serial number in an OCSP request differs from the serial number in the OCSP response.

Frequently asked questions

What is CVE-2021-37155?: wolfSSL 4.6.x through 4.7.x before 4.8.0 does not produce a failure outcome when the serial number in an OCSP request differs from the serial number in the OCSP response.
How severe is CVE-2021-37155?: CVE-2021-37155 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-37155 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-37155?: CVE-2021-37155 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-37155?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-37155 published?: CVE-2021-37155 was published on 2021-07-21 and last updated on 2026-06-17.

References

Affected products (1)

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

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