CVE-2021-45338

Name: CVE-2021-45338
Creator: NVD / NIST
Published: 2021-12-27T14:15:08.17+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 0.38%

Last modified Jun 17, 2026

CVE-2021-45338 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 0.38% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.8/10

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

EPSS Probability

0.38%

29.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Avast	Antivirus	< 20.4

References

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

Timeline

Published: Dec 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-45338?

How severe is CVE-2021-45338?

CVE-2021-45338 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2021-45338?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-45338?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST