GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2021-26734 (GCVE-0-2021-26734)

Vulnerability from cvelistv5 – Published: 2023-10-23 13:18 – Updated: 2024-09-17 13:46
VLAI
Title
Junction Delete leading to elevation of privilege
Summary
Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-09-11 20:17 UTC
CWE
  • CWE-269 - Improper Privilege Management
Impacted products
Vendor Product Version CPE status
Zscaler Client Connector Affected: 0 , < 3.4.0.124 (custom)
guessed Create a notification for this product.
Show details on NVD website

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T20:33:40.861Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2021-26734",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-09-11T20:17:30.565473Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2024-09-17T13:46:22.720Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Client Connector",
          "vendor": "Zscaler",
          "versions": [
            {
              "lessThan": "3.4.0.124",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "user": "00000000-0000-4000-9000-000000000000",
          "value": "Benjamin Dubost, LMCO"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\u003cbr\u003e\n\n\u003cbr\u003e\n\n"
            }
          ],
          "value": "Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\n\n\n\n\n\n"
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-233",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-233 Privilege Escalation"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 4.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-269",
              "description": "CWE-269 Improper Privilege Management",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2023-10-23T13:18:36.569Z",
        "orgId": "73c6f63b-efac-410d-a0a9-569700f85a04",
        "shortName": "Zscaler"
      },
      "references": [
        {
          "url": "https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Junction Delete leading to elevation of privilege",
      "x_generator": {
        "engine": "Vulnogram 0.1.0-dev"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "73c6f63b-efac-410d-a0a9-569700f85a04",
    "assignerShortName": "Zscaler",
    "cveId": "CVE-2021-26734",
    "datePublished": "2023-10-23T13:18:36.569Z",
    "dateReserved": "2021-02-05T20:34:27.823Z",
    "dateUpdated": "2024-09-17T13:46:22.720Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2021-26734",
      "date": "2026-09-17",
      "epss": "0.00142",
      "percentile": "0.03906"
    },
    "fkie_nvd": {
      "configurations": "[{\"nodes\": [{\"operator\": \"OR\", \"negate\": false, \"cpeMatch\": [{\"vulnerable\": true, \"criteria\": \"cpe:2.3:a:zscaler:client_connector:*:*:*:*:*:windows:*:*\", \"versionEndExcluding\": \"3.4.0.124\", \"matchCriteriaId\": \"8318DD99-D4B2-4917-AAB3-56D65DE97B57\"}]}]}]",
      "descriptions": "[{\"lang\": \"en\", \"value\": \"Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\\n\\n\\n\\n\\n\\n\"}, {\"lang\": \"es\", \"value\": \"El instalador de Zscaler Client Connector en Windows anterior a la versi\\u00f3n 3.4.0.124 manejaba incorrectamente las uniones de directorios durante la desinstalaci\\u00f3n. Un adversario local puede eliminar carpetas en un contexto elevado.\"}]",
      "id": "CVE-2021-26734",
      "lastModified": "2024-11-21T05:56:46.477",
      "metrics": "{\"cvssMetricV31\": [{\"source\": \"cve@zscaler.com\", \"type\": \"Secondary\", \"cvssData\": {\"version\": \"3.1\", \"vectorString\": \"CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H\", \"baseScore\": 4.4, \"baseSeverity\": \"MEDIUM\", \"attackVector\": \"LOCAL\", \"attackComplexity\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"userInteraction\": \"REQUIRED\", \"scope\": \"UNCHANGED\", \"confidentialityImpact\": \"NONE\", \"integrityImpact\": \"NONE\", \"availabilityImpact\": \"HIGH\"}, \"exploitabilityScore\": 0.8, \"impactScore\": 3.6}, {\"source\": \"nvd@nist.gov\", \"type\": \"Primary\", \"cvssData\": {\"version\": \"3.1\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N\", \"baseScore\": 5.5, \"baseSeverity\": \"MEDIUM\", \"attackVector\": \"LOCAL\", \"attackComplexity\": \"LOW\", \"privilegesRequired\": \"NONE\", \"userInteraction\": \"REQUIRED\", \"scope\": \"UNCHANGED\", \"confidentialityImpact\": \"NONE\", \"integrityImpact\": \"HIGH\", \"availabilityImpact\": \"NONE\"}, \"exploitabilityScore\": 1.8, \"impactScore\": 3.6}]}",
      "published": "2023-10-23T14:15:08.927",
      "references": "[{\"url\": \"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\", \"source\": \"cve@zscaler.com\", \"tags\": [\"Release Notes\"]}, {\"url\": \"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\", \"source\": \"af854a3a-2127-422b-91ae-364da2661108\", \"tags\": [\"Release Notes\"]}]",
      "sourceIdentifier": "cve@zscaler.com",
      "vulnStatus": "Modified",
      "weaknesses": "[{\"source\": \"cve@zscaler.com\", \"type\": \"Secondary\", \"description\": [{\"lang\": \"en\", \"value\": \"CWE-269\"}]}, {\"source\": \"nvd@nist.gov\", \"type\": \"Primary\", \"description\": [{\"lang\": \"en\", \"value\": \"NVD-CWE-noinfo\"}]}]"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2021-26734\",\"sourceIdentifier\":\"cve@zscaler.com\",\"published\":\"2023-10-23T14:15:08.927\",\"lastModified\":\"2024-11-21T05:56:46.477\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\\n\\n\\n\\n\\n\\n\"},{\"lang\":\"es\",\"value\":\"El instalador de Zscaler Client Connector en Windows anterior a la versi\u00f3n 3.4.0.124 manejaba incorrectamente las uniones de directorios durante la desinstalaci\u00f3n. Un adversario local puede eliminar carpetas en un contexto elevado.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"cve@zscaler.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H\",\"baseScore\":4.4,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":0.8,\"impactScore\":3.6},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"cve@zscaler.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-269\"}]},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:zscaler:client_connector:*:*:*:*:*:windows:*:*\",\"versionEndExcluding\":\"3.4.0.124\",\"matchCriteriaId\":\"8318DD99-D4B2-4917-AAB3-56D65DE97B57\"}]}]}],\"references\":[{\"url\":\"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\",\"source\":\"cve@zscaler.com\",\"tags\":[\"Release Notes\"]},{\"url\":\"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Release Notes\"]}]}}",
    "redhat_vex": {
      "current_release_date": "2025-05-29T04:23:03+00:00",
      "cve": "CVE-2021-26734",
      "id": "CVE-2021-26734",
      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Junction Delete leading to elevation of privilege",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-26734.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\", \"tags\": [\"x_transferred\"]}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2024-08-03T20:33:40.861Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2021-26734\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2024-09-11T20:17:30.565473Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2024-09-17T13:46:11.512Z\"}}], \"cna\": {\"title\": \"Junction Delete leading to elevation of privilege\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"user\": \"00000000-0000-4000-9000-000000000000\", \"value\": \"Benjamin Dubost, LMCO\"}], \"impacts\": [{\"capecId\": \"CAPEC-233\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-233 Privilege Escalation\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 4.4, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"REQUIRED\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"vendor\": \"Zscaler\", \"product\": \"Client Connector\", \"versions\": [{\"status\": \"affected\", \"version\": \"0\", \"lessThan\": \"3.4.0.124\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://help.zscaler.com/zscaler-client-connector/client-connector-app-release-summary-2021\"}], \"x_generator\": {\"engine\": \"Vulnogram 0.1.0-dev\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\\n\\n\\n\\n\\n\\n\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Zscaler Client Connector Installer on Windows before version 3.4.0.124 improperly handled directory junctions during uninstallation. A local adversary may be able to delete folders in an elevated context.\u003cbr\u003e\\n\\n\u003cbr\u003e\\n\\n\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-269\", \"description\": \"CWE-269 Improper Privilege Management\"}]}], \"providerMetadata\": {\"orgId\": \"73c6f63b-efac-410d-a0a9-569700f85a04\", \"shortName\": \"Zscaler\", \"dateUpdated\": \"2023-10-23T13:18:36.569Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-26734\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2024-09-17T13:46:22.720Z\", \"dateReserved\": \"2021-02-05T20:34:27.823Z\", \"assignerOrgId\": \"73c6f63b-efac-410d-a0a9-569700f85a04\", \"datePublished\": \"2023-10-23T13:18:36.569Z\", \"assignerShortName\": \"Zscaler\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Loading…

Detection rules are retrieved from Rulezet.

Loading…

Loading…

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.


Loading…