CVE-2026-18453Network attack vector

Unauthenticated LDAP server crash via reused NULL backend

Published Sep 7, 2026 · Updated Sep 9, 2026

NULL pointer dereference in 389 Directory Server allows remote attackers to crash the LDAP server through crafted search requests. The op_shared_search path stores a NULL backend for a paged-results slot after a USE_ONE_BACKEND search names a nonexistent backend, then passes it to slapi_be_Rlock when a second search reuses the slot. Default anonymous LDAP access makes the two-request sequence pre-authentication and stops directory lookups and dependent authentication until ns-slapd restarts, without reading or modifying data.

CVSS severity7.5
High
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in 389 Directory Server allows remote attackers to crash the LDAP server through crafted search requests. The op_shared_search path stores a NULL backend for a paged-results slot after a USE_ONE_BACKEND search names a nonexistent backend, then passes it to slapi_be_Rlock when a second search reuses the slot. Default anonymous LDAP access makes the two-request sequence pre-authentication and stops directory lookups and dependent authentication until ns-slapd restarts, without reading or modifying data.

The record

CVE
CVE-2026-18453
Published
Sep 7, 2026
Updated
Sep 9, 2026
Vendor
389 Directory Server
Product
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat Enterprise Linux 8.8 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Directory Server 11Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Directory Server 12Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnAffected versions are unavailable in this record.
389 Directory Server · Red Hat Directory Server 13Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.8 Telecommunications Update ServiceAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 7 Extended Lifecycle SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10.0 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.6 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

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Your stack

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