CVE-2021-40837Network attack vector

Scanner-service interruption via ACE decompression

Published Feb 9, 2022 · Updated Aug 4, 2024

Denial of service in the F-Secure Capricorn antivirus engine before update 2022-02-01_01 allows remote attackers to stop scanning. The engine stops its scanner service while decompressing a crafted ACE archive; F-Secure has not disclosed the underlying parsing error. Delivery can be remote, but the CNA vector requires low privileges and user interaction, and the interruption disables antivirus scanning rather than the host.

CVSS severity4.6
Medium
EPSS probability0.66%
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 Capricorn antivirus engine before update 2022-02-01_01 allows remote attackers to stop scanning. The engine stops its scanner service while decompressing a crafted ACE archive; F-Secure has not disclosed the underlying parsing error. Delivery can be remote, but the CNA vector requires low privileges and user interaction, and the interruption disables antivirus scanning rather than the host.

The record

CVE
CVE-2021-40837
Published
Feb 9, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 9, 2022CVE 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 vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
4.6F-SecureCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L

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

T1499Endpoint Denial of Service

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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