Security readout for executives and security teams
Plain-English summary
CVE-2021-4236 affects applications using github.com/ecnepsnai/web 1.4.0 WebSockets with an AuthenticateMethod hook. WebSocket paths may skip that authentication hook, which can cause a crash or let a user reach functionality without the expected authentication.
Executive priority
Prioritize assessment if the organization runs Go services using this library for authenticated WebSockets. The worst case is unauthorized access or service disruption, but scope is narrow and tied to specific WebSocket usage.
Technical view
The issue is limited to explicit WebSocket use with AuthenticateMethod. Because AuthenticateMethod is not executed for WebSockets, code expecting non-nil UserData may dereference nil, and authorization decisions depending on that hook may be bypassed.
Likely exposure
Exposure is likely only in Go applications that import github.com/ecnepsnai/web 1.4.0 and use WebSocket handlers with AuthenticateMethod-based authentication. Non-WebSocket request handlers are stated as not vulnerable.
Exploitation context
The CVSS vector indicates remote, unauthenticated, low-complexity exploitation potential. The bundle marks KEV as false and provides no cited evidence of active exploitation, so active exploitation should not be assumed.
Researcher notes
Do not generalize this to all routes in the library. The source states ordinary request handlers without explicit WebSocket use are not vulnerable. Evidence does not identify exploited deployments or affected versions beyond 1.4.0.
Mitigation direction
- Identify applications using github.com/ecnepsnai/web version 1.4.0.
- Review all WebSocket handlers using AuthenticateMethod hooks.
- Apply the referenced upstream commit or a vendor-supported release containing the fix.
- Do not rely on affected WebSocket AuthenticateMethod behavior for access control.
- Add defensive nil handling where UserData is consumed.
Validation and detection
- Inventory Go modules for github.com/ecnepsnai/web 1.4.0.
- Confirm whether the application explicitly registers WebSocket handlers.
- Check whether WebSocket authorization depends on AuthenticateMethod.
- Review code paths that assume UserData is non-nil.
- Verify the referenced fix is present in the deployed dependency.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-400: Exact CWE lookup
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Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-4236 mapping review
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Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/ecnepsnai/web/commit/5a78f8d5c41ce60dcf9f61aaf47a7a8dc3e0002fCVE reference
- https://pkg.go.dev/vuln/GO-2021-0107CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.