CVE-2025-4134

Update tampering via unverified file write

Published May 28, 2025 · Updated May 28, 2025

Unverified update-file write in Gen Digital Avast Business Antivirus 4.5.1 allows local users to spoof or tamper with VPS updates. The do_update_vps routine writes an update file without verifying it, allowing attacker-controlled content to replace or modify the expected VPS package. Exploitation requires a low-privileged local user and user interaction, and successful tampering can compromise antivirus confidentiality, integrity, and availability.

CVSS severity7.3
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unverified update-file write in Gen Digital Avast Business Antivirus 4.5.1 allows local users to spoof or tamper with VPS updates. The do_update_vps routine writes an update file without verifying it, allowing attacker-controlled content to replace or modify the expected VPS package. Exploitation requires a low-privileged local user and user interaction, and successful tampering can compromise antivirus confidentiality, integrity, and availability.

The record

CVE
CVE-2025-4134
Published
May 28, 2025
Updated
May 28, 2025
Vendor
Gen Digital
Product
Avast Business Antivirus
Classifications
CWE-552, CAPEC-148, T1565.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 28, 2025CVE publishedPublication date reported by the CVE source.
  2. May 28, 2025Record 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=4.5.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Gen Digital · Avast Business Antivirusversion=4.5.1

Published CVSS scores

7.3NortonLifeLock Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:R/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

CWE-552Files or Directories Accessible to External Parties
CAPEC-148Content Spoofing
T1565.001Stored Data Manipulation

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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