Is CVE-2021-3899 in the CISA KEV catalog?

No. CVE-2021-3899 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3899?

CVE-2021-3899 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2021-3899?

CVE-2021-3899 has an EPSS score of 0.38% (30th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3899?

Upgrade apport on ubuntu 16.04 to 2.20.1-0ubuntu2.30+esm4 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3899

HIGH

7.8

CVSS v3

NVD

Description

There is a race condition in the 'replaced executable' detection that, with the correct local configuration, allow an attacker to execute arbitrary code as root.

CWE-367TOCTOU Race Condition

How to fix

Remediation Available

apportUbuntu

Fixed in:2.20.1-0ubuntu2.30+esm4USN-6894-1

Fixed in:2.20.9-0ubuntu7.28USN-5427-1

Fixed in:2.20.11-0ubuntu27.24USN-5427-1

Fixed in:2.20.11-0ubuntu82.1USN-5427-1

python-apportUbuntu

Fixed in:2.20.1-0ubuntu2.30+esm4USN-6894-1

python3-apportUbuntu

Fixed in:2.20.1-0ubuntu2.30+esm4USN-6894-1

Fixed in:2.20.9-0ubuntu7.28USN-5427-1

Fixed in:2.20.11-0ubuntu27.24USN-5427-1

Fixed in:2.20.11-0ubuntu82.1USN-5427-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.38%probability of exploitation in 30 days

30thpercentile

Low risk: more likely to be exploited than 30% of all known CVEs.

References

Patch1

bugs.launchpad.net

Vendor Advisory1

ubuntu.com

Third-Party Advisory1

cve.org

Related Vulnerabilities

Other CWE-367 (TOCTOU Race Condition) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-36980	High	8.1	83%	-	Fix
CVE-2024-30088	High	7.0	68%	KEV + Ransom	Fix
CVE-2004-0594	Medium	5.1	55%	-	Fix
CVE-2024-50379	Critical	9.8	44%	-	Fix
CVE-2023-38146	High	8.8	39%	-	Fix
CVE-2024-0132	Critical	9.0	37%	-	Fix

Embed a live status badge for CVE-2021-3899

Markdown

[![CVE-2021-3899](https://tridentstack.com/cve/badge/CVE-2021-3899.svg)](https://tridentstack.com/cve/CVE-2021-3899)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-3899"><img src="https://tridentstack.com/cve/badge/CVE-2021-3899.svg" alt="CVE-2021-3899"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-08-26.