What’s Vulnerable › Vulnerabilities

CVE-2021-45338

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-27 · updated 2026-06-17

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.

Affected products

• Avast Antivirus: before 20.4 — fixed in 20.4

How to fix

Upgrade to a fixed version: Avast Antivirus 20.4. Check the vendor advisory for mitigations.

References

• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.1
• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.2
• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.3
• https://www.avast.com/hacker-hall-of-fame/en/researcher-david-eade-reports-antitrack-bug-to-avast-0
• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.1
• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.2
• https://github.com/the-deniss/Vulnerability-Disclosures/tree/main/CVE-2021-AVST1.3
• https://www.avast.com/hacker-hall-of-fame/en/researcher-david-eade-reports-antitrack-bug-to-avast-0

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