CVE-2021-3514Public exploitNetwork attack vector

Authenticated LDAP server crash via missing nsuniqueid

Published May 28, 2021 · Updated Aug 3, 2024

NULL pointer dereference in 389 Directory Server 1.4.3 allows remote authenticated users to crash the LDAP server with a crafted sync_repl query. While encoding a synchronization result, sync_create_state_control reads an nsuniqueid value without first verifying that the entry contains the attribute. The Content Synchronization request requires LDAP credentials, and successful exploitation terminates ns-slapd without reported data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

NULL pointer dereference in 389 Directory Server 1.4.3 allows remote authenticated users to crash the LDAP server with a crafted sync_repl query. While encoding a synchronization result, sync_create_state_control reads an nsuniqueid value without first verifying that the entry contains the attribute. The Content Synchronization request requires LDAP credentials, and successful exploitation terminates ns-slapd without reported data disclosure or modification.

The record

CVE
CVE-2021-3514
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
389 Directory Server
Product
389 Directory Server
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=389-ds-base 1.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

389 Directory Server · 389 Directory Serverversion=389-ds-base 1.4.3

Published CVSS scores

6.5SUSECVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.5NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0NVDAV:N/AC:L/Au:S/C:N/I:N/A:P

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 exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo