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Vulnerability record · CVE-2021-45335 · published 27 December 2021

CVE-2021-45335: Avast antivirus incorrect default permissions vulnerability

Avast · Antivirus

Sandbox component in Avast Antivirus prior to 20.4 has an insecure permission which could be abused by local user to control the outcome of scans, and therefore evade detection or delete arbitrary system files.

8.8 CVSS 3.1 High EPSS 0.38% · top 70.9% CWE-276 · Incorrect default permissions
8.8CVSS 3.1 base score, v2 7.2
0.38%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Sandbox component in Avast Antivirus prior to 20.4 has an insecure permission which could be abused by local user to control the outcome of scans, and therefore evade detection or delete arbitrary system files.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST3%20%26%20CVE-2021-AVST4%20%26%20CVE-2021 ExploitThird Party Advisory
https://www.avast.com/hacker-hall-of-fame/en/researcher-david-eade-reports-antitrack-bug-to-avast-0 Vendor Advisory
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST3%20%26%20CVE-2021-AVST4%20%26%20CVE-2021 ExploitThird Party Advisory
https://www.avast.com/hacker-hall-of-fame/en/researcher-david-eade-reports-antitrack-bug-to-avast-0 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-45335), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.