CVE-2021-40833: A vulnerability affecting F-Secure antivirus engine was discovered whereby unpacking UPX file can lead to deni

Routine

MEDIUM 5.5WATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2021-40833 is a medium-severity flaw (CVSS 5.5) affecting atlant, internet gatekeeper, linux security. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability affecting F-Secure antivirus engine was discovered whereby unpacking UPX file can lead to denial-of-service. The vulnerability can be exploited remotely by an attacker. A successful attack will result in denial-of-service of the antivirus engine.

Why this priority

On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-404
Published	2021-11-26
Last modified	2026-06-17

Publisher (CNA): F-Secure · Vendor: f-secure

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-11-26 17:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

f-secure atlant MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy atlant || rpm -q atlant || atlant --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

f-secure internet gatekeeper MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy internet-gatekeeper || rpm -q internet-gatekeeper || internet-gatekeeper --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

f-secure linux security MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy linux-security || rpm -q linux-security || linux-security --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

f-secure linux security 64 MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy linux-security-64 || rpm -q linux-security-64 || linux-security-64 --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

f-secure elements endpoint protection MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy elements-endpoint-protection || rpm -q elements-endpoint-protection || elements-endpoint-protection --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-40833?

atlant: mitigate or apply the listed mitigation; internet gatekeeper: mitigate or apply the listed mitigation; linux security: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-40833 being exploited?

CVE-2021-40833 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-40833 affect?

CVE-2021-40833 affects atlant, internet gatekeeper, linux security. Severity is medium (CVSS 5.5). A vulnerability affecting F-Secure antivirus engine was discovered whereby unpacking UPX file can lead to denial-of-service. The vulnerability can be exploited remotely by an attacker. A successful attack will result in denial-of-service of

How urgent is CVE-2021-40833?

Priority 33/100. On your watchlist

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References

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