Cyber Resilience

CVE-2021-4236

CriticalPublic PoC

Published: 27 December 2022

Published
27 December 2022
Modified
11 April 2025
KEV Added
Patch
CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0045 64.3th percentile
Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-4236 is a critical-severity NULL Pointer Dereference (CWE-476) vulnerability in Web Project Web. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 35.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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.…

more

Request handlers that do not explicitly use WebSockets are not vulnerable.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

web project
web
1.4.0 — 1.5.2

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References