Is CVE-2021-4091 in the CISA KEV catalog?

No. CVE-2021-4091 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-4091?

CVE-2021-4091 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2021-4091?

CVE-2021-4091 has an EPSS score of 1.98% (78th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-4091?

Upgrade 389-ds-base on debian 11 to 1.4.4.11-2+deb11u1 or later.

CVE & CISA-KEV Catalog

CVE-2021-4091

HIGHEPSS 78th pctl

7.5

CVSS v3

NVD

Description

A double-free was found in the way 389-ds-base handles virtual attributes context in persistent searches. An attacker could send a series of search requests, forcing the server to behave unexpectedly, and crash.

CWE-415

How to fix

Remediation Available

389-ds-baseDebian

Fixed in:1.4.4.11-2+deb11u1CVE-2021-4091

Fixed in:2.0.15-1CVE-2021-4091

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 VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

1.98%probability of exploitation in 30 days

78thpercentile

Elevated risk: more likely to be exploited than 78% of all known CVEs.

References

Patch1

bugzilla.redhat.com

Other references2

Related Vulnerabilities

Other CWE-415 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-25136	Medium	6.5	90%	-	Fix
CVE-2018-0101	Critical	10.0	87%	-	Fix
CVE-2003-0545	Critical	9.8	85%	-	Fix
CVE-2019-3829	Medium	5.3	59%	-	Fix
CVE-2026-33824	Critical	9.8	56%	-	Fix
CVE-2021-3407	Medium	5.5	50%	-	Fix

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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 2025-11-03.