CVE-2021-45336Public exploit

SYSTEM privilege escalation via Task Scheduler IPC

Published Dec 27, 2021 · Updated Aug 4, 2024

Privilege escalation in Avast Antivirus before 20.4 allows local users to escape the Sandbox component and execute code as SYSTEM. The sandboxed aswEngSrv.exe process retains a restricted SYSTEM token, and Task Scheduler checks only its SYSTEM owner when registering tasks. Code must already run inside the antivirus sandbox; registering a scheduled task then launches unrestricted attacker code as SYSTEM.

CVSS severity8.8
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in Avast Antivirus before 20.4 allows local users to escape the Sandbox component and execute code as SYSTEM. The sandboxed aswEngSrv.exe process retains a restricted SYSTEM token, and Task Scheduler checks only its SYSTEM owner when registering tasks. Code must already run inside the antivirus sandbox; registering a scheduled task then launches unrestricted attacker code as SYSTEM.

The record

CVE
CVE-2021-45336
Published
Dec 27, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284, T1053.005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 27, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1053.005Scheduled Task/Job: Scheduled Task

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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