CVE-2021-41526

Local SYSTEM privilege escalation via replaceable repair executable

Published Mar 29, 2023 · Updated Aug 4, 2024

Privilege escalation in Revenera InstallShield before 2021 R2 allows local users to gain SYSTEM privileges during MSI repair. During repair of an MSI built with an InstallScript custom action, engine files are extracted into the invoking user's TEMP directory and ISBEW64.EXE is run without protection from replacement. A low-privileged authenticated user must start repair and replace that executable before launch; successful exploitation executes attacker code as NT AUTHORITY\SYSTEM.

CVSS severity7.8
High
EPSS probability0.28%
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 Revenera InstallShield before 2021 R2 allows local users to gain SYSTEM privileges during MSI repair. During repair of an MSI built with an InstallScript custom action, engine files are extracted into the invoking user's TEMP directory and ISBEW64.EXE is run without protection from replacement. A low-privileged authenticated user must start repair and replace that executable before launch; successful exploitation executes attacker code as NT AUTHORITY\SYSTEM.

The record

CVE
CVE-2021-41526
Published
Mar 29, 2023
Updated
Aug 4, 2024
Vendor
Revenera
Product
InstallShield
Classifications
T1574.005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 29, 2023CVE 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2021
  2. Affected versionversion=2021

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Revenera · InstallShieldversion=0 <2021; version=2021

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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 exploitUnconfirmed

Weakness, pattern, technique

T1574.005Executable Installer File Permissions Weakness

Public exploit references

No public exploit references are available in this record.

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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