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CVE-2021-4236

Status: ModifiedCritical (9.8)—
Severity9.8Critical · CVSS 3.1
Exploitation probability1.15 %higher than 67% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found

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.

CVSS

Base score
9.8
Version
3.1
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days
1.15 %
Percentile among all scored CVEs
67
Score date
10/21/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

WEB Project — WEB

CWEs

References

Show 4 references

Raw JSON (NVD)

Show
{
  "id": "CVE-2021-4236",
  "cveTags": [],
  "metrics": {
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
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          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-04-11T16:20:37.403821Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
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          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
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  "affected": [
    {
      "source": "security@golang.org",
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        {
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          "product": "github.com/ecnepsnai/web",
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  "published": "2022-12-27T22:15:12.013",
  "references": [
    {
      "url": "https://github.com/ecnepsnai/web/commit/5a78f8d5c41ce60dcf9f61aaf47a7a8dc3e0002f",
      "tags": [
        "Patch",
        "Third Party Advisory"
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      "source": "security@golang.org"
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      "url": "https://pkg.go.dev/vuln/GO-2021-0107",
      "tags": [
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        "Patch",
        "Third Party Advisory"
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      "source": "security@golang.org"
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      "tags": [
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        "Patch",
        "Third Party Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "Web Sockets no ejecuta ningún método AuthenticateMethod que pueda configurarse, lo que lleva a una desreferencia del puntero null si se supone que el puntero UserData devuelto no es null, o a una omisión de autenticación. Este problema solo afecta a WebSockets con un enlace AuthenticateMethod. Los controladores de solicitudes que no utilizan WebSockets explícitamente no son vulnerables."
    }
  ],
  "lastModified": "2026-06-17T04:19:19.493",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:web_project:web:*:*:*:*:*:go:*:*",
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              "versionEndExcluding": "1.5.2",
              "versionStartIncluding": "1.4.0"
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          ],
          "operator": "OR"
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  ],
  "sourceIdentifier": "security@golang.org"
}