Vulnerability-Lookup

FKIE_CVE-2021-27241

Vulnerability from fkie_nvd - Published: 2021-03-29 21:15 - Updated: 2026-06-17 03:44

Severity

6.1 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Summary

This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security 20.8.2429 (Build 20.8.5653.561). An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-12082.

References

	URL	Tags
	zdi-disclosures@trendmicro.com	https://www.zerodayinitiative.com/advisories/ZDI-21-208/	Third Party Advisory, VDB Entry
	af854a3a-2127-422b-91ae-364da2661108	https://www.zerodayinitiative.com/advisories/ZDI-21-208/	Third Party Advisory, VDB Entry

Impacted products

	Vendor	Product	Version
	avast	premium_security	20.8.2429

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Premium Security",
          "vendor": "Avast",
          "versions": [
            {
              "status": "affected",
              "version": "20.8.2429 (Build 20.8.5653.561)"
            }
          ]
        }
      ],
      "source": "zdi-disclosures@trendmicro.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:avast:premium_security:20.8.2429:*:*:*:*:*:*:*",
              "matchCriteriaId": "2686D810-4654-4FF3-A785-A2B43139967E",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security 20.8.2429 (Build 20.8.5653.561). An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-12082."
    },
    {
      "lang": "es",
      "value": "Esta vulnerabilidad permite a atacantes locales eliminar directorios arbitrarios en las instalaciones afectadas de Avast Premium Security versi\u00f3n 20.8.2429 (Build 20.8.5653.561).\u0026#xa0;Un atacante primero debe obtener la capacidad de ejecutar c\u00f3digo poco privilegiado en el sistema de destino para explotar esta vulnerabilidad.\u0026#xa0;El fallo espec\u00edfico se presenta dentro del m\u00f3dulo AvastSvc.exe.\u0026#xa0;Al crear una uni\u00f3n de directorio, un atacante puede abusar del servicio para eliminar un directorio.\u0026#xa0;Un atacante puede aprovechar esta vulnerabilidad para crear una condici\u00f3n de denegaci\u00f3n de servicio en el sistema.\u0026#xa0;Era ZDI-CAN-12082"
    }
  ],
  "id": "CVE-2021-27241",
  "lastModified": "2026-06-17T03:44:31.850",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "LOW",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "LOCAL",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 3.6,
          "confidentialityImpact": "NONE",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:L/AC:L/Au:N/C:N/I:P/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV30": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
          "version": "3.0"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 4.2,
        "source": "zdi-disclosures@trendmicro.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 4.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-03-29T21:15:12.593",
  "references": [
    {
      "source": "zdi-disclosures@trendmicro.com",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "url": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory",
        "VDB Entry"
      ],
      "url": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/"
    }
  ],
  "sourceIdentifier": "zdi-disclosures@trendmicro.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-59"
        }
      ],
      "source": "zdi-disclosures@trendmicro.com",
      "type": "Secondary"
    }
  ]
}

CVE-2021-27241 (GCVE-0-2021-27241)

Vulnerability from cvelistv5 – Published: 2021-03-29 21:05 – Updated: 2024-08-03 20:48

Summary

Severity

6.1 (Medium)


                        
                          CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

CWE

CWE-59 - Improper Link Resolution Before File Access ('Link Following')

Assigner

zdi mitre root

References

1 reference

URL	Tags
https://www.zerodayinitiative.com/advisories/ZDI-…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
Avast	Premium Security	Affected: 20.8.2429 (Build 20.8.5653.561)

Credits

Abdelhamid Naceri

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T20:48:15.888Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
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              "x_transferred"
            ],
            "url": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Premium Security",
          "vendor": "Avast",
          "versions": [
            {
              "status": "affected",
              "version": "20.8.2429 (Build 20.8.5653.561)"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Abdelhamid Naceri"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security 20.8.2429 (Build 20.8.5653.561). An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-12082."
        }
      ],
      "metrics": [
        {
          "cvssV3_0": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.0"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-59",
              "description": "CWE-59: Improper Link Resolution Before File Access (\u0027Link Following\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-03-29T21:05:30.000Z",
        "orgId": "99f1926a-a320-47d8-bbb5-42feb611262e",
        "shortName": "zdi"
      },
      "references": [
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          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "zdi-disclosures@trendmicro.com",
          "ID": "CVE-2021-27241",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "Premium Security",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "20.8.2429 (Build 20.8.5653.561)"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "Avast"
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        },
        "credit": "Abdelhamid Naceri",
        "data_format": "MITRE",
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        "data_version": "4.0",
        "description": {
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              "lang": "eng",
              "value": "This vulnerability allows local attackers to delete arbitrary directories on affected installations of Avast Premium Security 20.8.2429 (Build 20.8.5653.561). An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the AvastSvc.exe module. By creating a directory junction, an attacker can abuse the service to delete a directory. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-12082."
            }
          ]
        },
        "impact": {
          "cvss": {
            "vectorString": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.0"
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        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "CWE-59: Improper Link Resolution Before File Access (\u0027Link Following\u0027)"
                }
              ]
            }
          ]
        },
        "references": {
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            {
              "name": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/",
              "refsource": "MISC",
              "url": "https://www.zerodayinitiative.com/advisories/ZDI-21-208/"
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  "cveMetadata": {
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    "dateReserved": "2021-02-16T00:00:00.000Z",
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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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.