CVE-2021-33599Network attack vector

Antivirus engine hang via crafted WIM archive

Published Sep 7, 2021 · Updated Aug 3, 2024

Denial of service in the F-Secure Antivirus engine in Atlant allows remote authenticated users to freeze scanning with a crafted WIM archive. The engine's WIM-scanning path enters an infinite loop on crafted archive content instead of terminating the scan. The archive must reach an affected engine for scanning; successful exploitation hangs the antivirus engine without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the F-Secure Antivirus engine in Atlant allows remote authenticated users to freeze scanning with a crafted WIM archive. The engine's WIM-scanning path enters an infinite loop on crafted archive content instead of terminating the scan. The archive must reach an affected engine for scanning; successful exploitation hangs the antivirus engine without reported data disclosure or modification.

The record

CVE
CVE-2021-33599
Published
Sep 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.6F-SecureCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
4.3NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

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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