CVE-2021-4091

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.

Published: 2022-02-18 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-4091 is rated Moderate Risk (49.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.34%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-4091

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-01 0.24% 0.34% +0.11%
2 2025-11-21 1.56% 0.24% -1.32%
3 2025-11-18 — 1.56% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4091

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-4091

OS Trackers for CVE-2021-4091

vendor priority summary link
debian not yet assigned CVE-2021-4091 not yet assigned priority: Debian including 1 source packages (389-ds-base), 4 status rows across 4 suites (bookworm, bullseye, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2021-4091
redhat low — https://access.redhat.com/security/cve/CVE-2021-4091
suse medium CVE-2021-4091 severity moderate: SUSE including 44 source package names (2.0-14.9:389-ds-2.0.15~git26.1ea6a6803-150400.3.5.1, 2.0-14.9:lib389-2.0.15~git26.1ea6a6803-150400.3.5.1, …), 127 product×package rows across 30 product lines (Container suse/389-ds, SUSE CaaS Platform 4.0, … (30 product lines)): Fixed 127. https://www.suse.com/security/cve/CVE-2021-4091/
ubuntu medium CVE-2021-4091 medium priority: Ubuntu including 1 source packages (389-ds-base), 14 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 7, needs-triage 7. https://ubuntu.com/security/CVE-2021-4091

Affected software / configurations for CVE-2021-4091

Vendor Product Version Raw CPE
port389 389-ds-base < 1.3.10.2 cpe:2.3:a:port389:389-ds-base:*:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 7 cpe:2.3:o:redhat:enterprise_linux_desktop:7:*:*:*:*:*:*:*
redhat enterprise_linux_for_ibm_z_systems 7.0 cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_big_endian 7.0 cpe:2.3:o:redhat:enterprise_linux_for_power_big_endian:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_power_little_endian 7.0 cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_for_scientific_computing 7.0 cpe:2.3:o:redhat:enterprise_linux_for_scientific_computing:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 7.0 cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*

References for CVE-2021-4091

cvelogic Threat Intelligence