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Vulnerability record · CVE-2021-45338 · published 27 December 2021

CVE-2021-45338: Avast antivirus vulnerability

Avast · Antivirus

Multiple privilege escalation vulnerabilities in Avast Antivirus prior to 20.4 allow a local user to gain elevated privileges by calling unnecessarily powerful internal methods of the main antivirus service which could lead to the (1) arbitrary file delete, (2) write and (3) reset security.

7.8 CVSS 3.1 High EPSS 0.38% · top 70.6%
7.8CVSS 3.1 base score, v2 7.2
0.38%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 6 tagged exploit
17 Jun 2026Last modified by NVD

Description

Multiple privilege escalation vulnerabilities in Avast Antivirus prior to 20.4 allow a local user to gain elevated privileges by calling unnecessarily powerful internal methods of the main antivirus service which could lead to the (1) arbitrary file delete, (2) write and (3) reset security.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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-AVST1.1 ExploitThird Party Advisory
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.2 ExploitThird Party Advisory
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.3 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-AVST1.1 ExploitThird Party Advisory
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.2 ExploitThird Party Advisory
https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.3 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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Related vulnerabilities

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

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Source: NIST National Vulnerability Database (record CVE-2021-45338), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.