How severe is CVE-2021-4236?

CVE-2021-4236 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-2021-4236 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4236?

CVE-2021-4236 affects Web Project Web. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4236?

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-2021-4236 published?

CVE-2021-4236 was published on 2022-12-27 and last updated on 2026-06-17.

CVE-2021-4236

CVE-2021-4236 is a critical-severity vulnerability in Web Project Web 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. The underlying weakness is classified as CWE-476.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Web Project Web
Published: 2022-12-27
Last modified: 2026-06-17

Description

Web Sockets do not execute any AuthenticateMethod methods which may be set, leading to a nil pointer dereference if the returned UserData pointer is assumed to be non-nil, or authentication bypass. This issue only affects WebSockets with an AuthenticateMethod hook. Request handlers that do not explicitly use WebSockets are not vulnerable.

Frequently asked questions

What is CVE-2021-4236?: Web Sockets do not execute any AuthenticateMethod methods which may be set, leading to a nil pointer dereference if the returned UserData pointer is assumed to be non-nil, or authentication bypass. This issue only affects WebSockets with an AuthenticateMethod hook. Request handlers that do not explicitly use WebSockets are not vulnerable.
How severe is CVE-2021-4236?: CVE-2021-4236 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-2021-4236 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4236?: CVE-2021-4236 affects Web Project Web. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4236?: 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-2021-4236 published?: CVE-2021-4236 was published on 2022-12-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:web_project:web:*:*:*:*:*:go:*:*

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