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CVE-2020-11633

Status: ModifiedCritical (9.8)—

The Zscaler Client Connector for Windows prior to 2.1.2.74 had a stack based buffer overflow when connecting to misconfigured TLS servers. An adversary would potentially have been able to execute arbitrary code with system privileges.

CVSS

Exploitation probability (EPSS)

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)

Zscaler — Client Connector

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2020-11633",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 10,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:C/I:C/A:C",
          "authentication": "NONE",
          "integrityImpact": "COMPLETE",
          "accessComplexity": "LOW",
          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "COMPLETE"
        },
        "acInsufInfo": false,
        "impactScore": 10,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "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"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cve@zscaler.com",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-07-15T18:15:08.643",
  "references": [
    {
      "url": "https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2020?applicable_category=Windows&applicable_version=2.1.2.81",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve@zscaler.com"
    },
    {
      "url": "https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2020?applicable_category=Windows&applicable_version=2.1.2.81",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-787"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Zscaler Client Connector for Windows prior to 2.1.2.74 had a stack based buffer overflow when connecting to misconfigured TLS servers. An adversary would potentially have been able to execute arbitrary code with system privileges."
    },
    {
      "lang": "es",
      "value": "El Zscaler Client Connector para Windows anterior a versión 2.1.2.74, presentaba un desbordamiento de búfer en la región stack de la memoria cuando se conectaba a servidores TLS mal configurados. Un adversario podría potencialmente haber podido ejecutar código arbitrario con privilegios del sistema"
    }
  ],
  "lastModified": "2026-06-17T02:50:31.507",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:zscaler:client_connector:*:*:*:*:*:windows:*:*",
              "vulnerable": true,
              "matchCriteriaId": "811027D2-BD8F-482D-A425-C58BB48CF986",
              "versionEndExcluding": "2.1.2.81"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@zscaler.com"
}