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389 Directory Server CVE-2026-9064

| EUVDEUVD-2026-31079 HIGH
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-05-20 secalert@redhat.com GHSA-7r3c-wfgh-x96c
Denial Of Service Directory Server 389 Directory Server Enterprise Linux
7.5
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

1
Analysis Generated
May 20, 2026 - 10:31 vuln.today

DescriptionCVE.org

A flaw was found in 389-ds-base. The get_ldapmessage_controls_ext() function in the LDAP server does not enforce an upper bound on the number of controls per LDAP message. A remote, unauthenticated attacker can send a specially crafted LDAP request containing hundreds of thousands of minimal controls within the default maximum BER message size (2 MB), causing excessive CPU consumption and heap allocation on the server. Under concurrent exploitation, this leads to significant latency degradation, worker thread starvation, or out-of-memory termination, resulting in a denial of service.

AnalysisAI

Denial of service in 389-ds-base LDAP server allows remote unauthenticated attackers to exhaust CPU and heap memory by sending a single LDAP request packed with hundreds of thousands of minimal controls. Because get_ldapmessage_controls_ext() does not cap the per-message control count, the 2 MB default BER message limit is the only ceiling, and concurrent abuse causes worker thread starvation or OOM termination. No public exploit identified at time of analysis, and the issue is not on CISA KEV.

Technical ContextAI

389 Directory Server (389-ds-base) is the open-source LDAP v3 directory server maintained by Red Hat and used as the upstream for Red Hat Directory Server and FreeIPA. LDAP messages carry an optional sequence of controls (RFC 4511 §4.1.11) parsed via BER decoding; the affected get_ldapmessage_controls_ext() routine iterates and allocates per-control structures without bounding the iteration count. This is a classic CWE-770 (Allocation of Resources Without Limits or Throttling) condition: the default 2 MB nsslapd-maxbersize cap on inbound messages permits roughly 10^5-10^6 trivially encoded controls per request, each forcing heap allocation and CPU work in the parser before any access control evaluation occurs.

RemediationAI

No vendor-released patch identified at time of analysis from the provided references; monitor https://access.redhat.com/security/cve/CVE-2026-9064 and https://bugzilla.redhat.com/show_bug.cgi?id=2480093 for the fixed 389-ds-base package version and apply the corresponding RHSA once released. As a compensating control, reduce the inbound message ceiling by lowering nsslapd-maxbersize from its 2 MB default (e.g., to 209715 / 200 KB) to shrink the attainable control count per request - note this will break legitimate clients that send large modifications or bulk attribute writes, so test against your replication and provisioning workflows first. Restrict TCP/389 and TCP/636 at the network layer to known client subnets and place the directory behind a load balancer or LDAP proxy that can enforce per-source request rate limits, accepting the trade-off that proxies add a hop and may interfere with StartTLS or SASL-bound clients. As a last resort during active abuse, raise nsslapd-threadnumber and nsslapd-maxdescriptors to delay thread starvation, understanding this only buys time and increases memory pressure.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Server Applications 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed
SUSE Linux Enterprise Server 16.0 Fixed
SUSE Linux Enterprise Server 16.1 Fixed

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CVE-2026-9064 vulnerability details – vuln.today
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