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Red Hat Directory Server CVE-2026-16560

| EUVDEUVD-2026-47661 MEDIUM
Insufficient Granularity of Access Control (CWE-1220)
2026-07-22 redhat GHSA-cwj4-7fp9-r4jg
5.3
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
vuln.today AI
6.5 MEDIUM

AV:N and PR:N per LDAP exposure; I:L added because description explicitly cites arbitrary memory write as a possible outcome alongside DoS.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.3 MEDIUM
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Lifecycle Timeline

2
Analysis Generated
Jul 22, 2026 - 13:46 vuln.today
CVE Published
Jul 22, 2026 - 12:51 cve.org
MEDIUM 5.3

DescriptionCVE.org

A heap-buffer-overflow flaw was found in Directory Server (389-ds-base). When a DN contains a legacy-quoted value, the server won't close the heap allocation allowing another call to refer to the same memory pointer causing a denial of service or an arbitrary memory write operation.

AnalysisAI

Heap buffer overflow in Red Hat Directory Server (389-ds-base) exposes LDAP services to remote unauthenticated denial of service or potential arbitrary memory write via malformed DN input. When a Distinguished Name containing a legacy-quoted value is processed, the server fails to close the associated heap allocation, permitting a subsequent operation to reference the same memory pointer - a classic heap confusion primitive. No public exploit has been identified at time of analysis, and this vulnerability is not listed in CISA KEV, though the network-accessible unauthenticated attack surface warrants prompt patching for any externally reachable Directory Server deployment.

Technical ContextAI

389-ds-base is the upstream FOSS project underlying Red Hat Directory Server (RHDS) and the LDAP directory service bundled across Red Hat Enterprise Linux 6 through 10. The vulnerability resides in the DN (Distinguished Name) parsing subsystem, specifically in handling of legacy-quoted attribute values - a notation style carried forward from older LDAPv2/X.500 syntax still accepted by the server for backward compatibility. The parser allocates heap memory for the quoted DN component but fails to properly deallocate it before returning, leaving the pointer live. A subsequent call can then obtain or dereference the same heap region, producing a double-use heap condition. The assigned CWE is CWE-1220 (Insufficient Granularity of Access Control), which does not map cleanly to the described heap mismanagement behavior; the root cause more accurately resembles CWE-122 (Heap-based Buffer Overflow) or a use-after-free pattern. This discrepancy should be noted when correlating with scanner output. The vulnerability is reachable over standard LDAP ports (389 plaintext, 636 TLS), making it network-accessible to any client permitted to submit LDAP requests.

RemediationAI

Apply the vendor-supplied updated RPM for 389-ds-base as documented in the Red Hat security advisory at https://access.redhat.com/security/cve/CVE-2026-16560. Exact fixed package versions are not confirmed from the data available at time of analysis - the Bugzilla entry at https://bugzilla.redhat.com/show_bug.cgi?id=2506102 and the advisory errata should be checked for the specific NVR (name-version-release) to target. As a compensating control while patching is arranged, restrict network access to LDAP ports 389 and 636 via host-based firewall (firewalld/iptables) or perimeter controls, permitting only known trusted LDAP clients - this eliminates unauthenticated remote exploitation since the vulnerability is exposed over the LDAP protocol. Trade-off: any application, authentication service, or client relying on LDAP queries from outside the allowlisted range will lose access. Additionally, disabling anonymous LDAP binds (if operationally viable) adds an authentication barrier, though the CVSS PR:N metric indicates authentication may not be a prerequisite for the triggering path. Legacy-quoted DN syntax processing may be configurable in some 389-ds-base versions; consult the upstream documentation to determine if it can be disabled, keeping in mind this may break legacy LDAP clients.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.1 Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP7 Affected

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CVE-2026-16560 vulnerability details – vuln.today

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